Syndacate

Yeah, so I drove my new Tercel 280 miles no problems with my friend to pick up the title on his car (that he's picking up today) - did up to 90mph on the highway - no problems.

I'm dropping him off - PULLING INTO HIS DRIVEWAY - I throw a CEL (note that his house isn't even a mile from mine ) - which kinda sux b/c I gotta get this thing inspected in the next 9 days and in NY for OBD-II vehicles the CEL needs to be off.

So I hooked it up to my OBD-II scanner, the catalyst I/M Monitor was the only one that wasn't ready (and I've seen that take a few hundred miles to ready quite a few times - that's no big deal, but the code...the code was a P0130 - "Oxygen Sensor 1 on bank 1 circuit" - though that's according to the OBD-II scanner, on H-T apparently that code doesn't exist, though I found the "subs" of that code which is:
"P0131 Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Circuit Low Voltage"

What the **** does low voltage mean? (The other one is P0133 or some **** like that which is high voltage). Does this mean new O2 time, or is this an electrical issue??

xXSilentScreamXx

new one

slowcivic2k

Could be both, high resistance in an electrical circuit will cause voltage loss, which is common with O2 sensors that have been spliced to fit, given the little voltage it produces a nick can cause some serious variations.

It could also means a bad O2, but the most definitive way of determining that is checking the cycle speed of the O2, in other words how fast it cycles from .9-1.0v down to .1-.2v and back. That test can be performed while the car is running with a good multimeter.

Sometimes replacement O2 sensors can be biased to high voltage, or low, in which is doesn't cycle from .1v to 1.0v like it should, but rather .1v to .5v, or high voltage would be .5v to 1.0v.

King V

Just take out the cluster and pull the bulb for the CEL. Har har.

slowcivic2k

And watch your mpg go down the drain.... nice answer...

MatterMatt

P0130 is pretty much just a generic 02 sensor code that aftermarket scan tools show because they can't identify the specific 02 fault. Your best bet is to determine exactly what the code is for (i.e. heater malfunction, slow circuit response, circuit low voltage, etc.). You should find out the specific code and start from there.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MatterMatt &raquo;</TD></TR><TR><TD CLASS="quote">P0130 is pretty much just a generic 02 sensor code that aftermarket scan tools show because they can't identify the specific 02 fault. Your best bet is to determine exactly what the code is for (i.e. heater malfunction, slow circuit response, circuit low voltage, etc.). You should find out the specific code and start from there. </TD></TR></TABLE>

So you're saying I got a cheap scanner and it didn't work right etc. etc. etc.

Thanks...

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowcivic2k &raquo;</TD></TR><TR><TD CLASS="quote">Could be both, high resistance in an electrical circuit will cause voltage loss, which is common with O2 sensors that have been spliced to fit, given the little voltage it produces a nick can cause some serious variations.

It could also means a bad O2, but the most definitive way of determining that is checking the cycle speed of the O2, in other words how fast it cycles from .9-1.0v down to .1-.2v and back. That test can be performed while the car is running with a good multimeter.

Sometimes replacement O2 sensors can be biased to high voltage, or low, in which is doesn't cycle from .1v to 1.0v like it should, but rather .1v to .5v, or high voltage would be .5v to 1.0v.</TD></TR></TABLE>

That's what I was thinking, I used my cheap *** scan tool to check the O2 sensor voltage and it was running at .4 - though that was AFTER the CEL came on and I reset it and all.

I drove it maybe 300 miles yeseterday and no CEL. I was thinking the circuit just came up b/c of the O2 sensor, but since an OEM Toyota O2 sensor is ~100 bucks (from a wholesale website) I wasn't ready to drop that if it was a one time deal. My gas mileage is excellent. I drove approximately ~500 miles in the last 2 days, I started on 1/4 tank - my tank is currently on "F" - and I only spent ~65 dollars in gas - I didn't even spend it - my friend who I was driving with to pick up the car did.

The gas mileage = OWNAGE on that car. I can't wait to get an accurate reading based on fill-to-fill .

So like, does this mean the O2 sensor is going out the door, or is it that sometimes the CEL will come on and it's not a big deal? I was thinking about just waiting on it and if it comes on again then ordering another one.

I mean it was weird, I drove like 200 miles the day before yes, and nothing, stopped to drop my neighbor/friend off, and the CEL came on, went home (&lt;1 mile), reset it, drove 300 miles yesterday, no CEL.

So should I just wait on it and if it keeps coming back on replace it? I'll check to see if the last one was plugged in there or spliced. I'll spray some contact cleaner on it too. If it keeps coming back on I'll replace I suppose .

MatterMatt

I wasn't saying you have a "cheap *** scan tool". The Autozone scanners, and even the $5000 Snap-On and Mac scan tools throw that same code because their software can't read some manufacturer's data well enough to pull specific system codes. For instance, the P1300 02 code, or P0700 AT system failure code, and many other "manufacturer controlled" dtcs.

Many 02 sensor codes are 2 trip DTCs, meaning it will take more than one failed drive cycle to set a permanent DTC that turns on the check engine light. Even if you reset the code and drove 300 miles, there may be a temporary DTC with no light. The next time you drive it and the conditions meet the enable criteria for the system to run the test, if it fails under similar conditions to the temporary DTC the light will turn on. They don't have to be consecutive drive cycles either, just similar conditions.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MatterMatt &raquo;</TD></TR><TR><TD CLASS="quote">I wasn't saying you have a "cheap *** scan tool". The Autozone scanners, and even the $5000 Snap-On and Mac scan tools throw that same code because their software can't read some manufacturer's data well enough to pull specific system codes. For instance, the P1300 02 code, or P0700 AT system failure code, and many other "manufacturer controlled" dtcs.

Many 02 sensor codes are 2 trip DTCs, meaning it will take more than one failed drive cycle to set a permanent DTC that turns on the check engine light. Even if you reset the code and drove 300 miles, there may be a temporary DTC with no light. The next time you drive it and the conditions meet the enable criteria for the system to run the test, if it fails under similar conditions to the temporary DTC the light will turn on. They don't have to be consecutive drive cycles either, just similar conditions. </TD></TR></TABLE>

I don't know what drive cycles and all that crap means - but it seems you're saying it'll come back on after starting it a second time. That 500 miles included turning it off and starting it at least 15 times.

MatterMatt

Mileage and the number of times you key the car on and off doesn't matter. If the car is driven and it sets a temporary DTC, it won't turn on the light. But if the car is driven any arbitrary number of times after having set that temporary DTC, and the ECM runs the 02 system test and it fails under similar conditions to the the temporary DTC, it will turn the check engine light on.

So in a nutshell, yes the light will come back on IF it fails twice under similar conditions. If your scan tool does not have the ability to read temporary DTCs or give freeze frame data with the DTCs then you won't be able to determine when and why that might happen. Its not crap, its just good old fashioned DTC troubleshooting.

slowcivic2k

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">I don't know what drive cycles and all that crap means - but it seems you're saying it'll come back on after starting it a second time. That 500 miles included turning it off and starting it at least 15 times.</TD></TR></TABLE>

A drive cycle is when all of the engines required monitors are checked while the vehicle is still running, to determine if they work, using rationality, and connectivity, once their enabling criteria are met.

Don't confuse this with a warm up cycle, in which the ECT simply cycles from its minimum temp, to normal operating temp.

A trip is when the key is off, turned to on, and a certain monitor is allowed to run, and then the key turned off. Sometimes running around the block will only allow one monitor to run, say the O2, because the engine was not running at the required criteria to test everything. (like the Catalyst Efficiency Monitor, which cannot be tested cold) That would consist of one trip for that monitor, if it failed, it will throw a DTC. If it fails the next time, you get another code, a freeze frame of the conditions that caused it to fail, and the MIL comes on.

The paper clip self check will also uncover a first-trip fault, in which a code is stored (and readable with the MIL) and then when the PCM determines that a fault does exist (by failing the monitor again, or second-trip), it will turn on the MIL. Sometimes the problem will clear itself, say for instance, that your PCM failed the O2 monitor two times (two trips), and the MIL comes on. If the same failure is not reported in 3 consecutive drive cycles which allows the O2 monitor to run again, the MIL will turn itself off, but the DTC will still remain, for another 37 consecutive drive cycles without the same problem, then it will delete it on its own.

Syndacate

I have an OBD-II scanner.

All my I/M monitors are reading "ok" but I have one "incomplete" (catalyst monitor) - which from my short experience with OBD-II cars, takes awhile to clear up anyways.

I ran a scan on the O2 sensors and the #1 o2 sensor gave me a .4v - and you said between .1 and .5 is normal.

I know about that last paragraph, "pending codes" is what they're referred to.

The OBD-II scanner can also read pending codes - that won't throw the CEL (temp codes that will clear themselves up after X number of drive cycles).

I'm throwing no MIL/CEL's
I'm thoriwng no pending codes

All but 1 monitor (catalyst efficiency) are "ok", only 1 is incomplete.

I'm not that smart, wanna clue me in on what the hell a DTC is? I assume that means "drive cycle" - but I'm not sure (this ****'s all new to me).

So if I'm understanding the two of you correctly, after it checks all the I/M monitors 37 times, the pending code (if it had one) would disappear?

Right now after I reset (been about 300 miles) I do not have any pending codes, and I do not have any hard codes. I don't know how many times it duty cycled, there might be a way to check it if I mess around with the scanner, though I don't think it'll matter much as long as there's no pending code, right?

It might have been just a glitch...but in my experience glitches don't just "happen." - y'kno?

I pulled out the O2 sensor plug and sprayed it w/ contact cleaner...maybe that'll make a difference, maybe it won't, but it's going good right now.

ECU requirements for NY OBD-II '96-'00 are that there's no CEL (you're allowed to have pending codes though), and that you have NO MORE than two (2) I/M Monitors incomplete.

Right now since there's no CEL (or a pending code for that matter) and there's only 1 incomplete it can be inspected (I'm taking it there Monday) - though I'm still a bit concerned.

slowcivic2k

I know you have a obd2 tool, im just saying that you can uncover a one trip fault with a paperclip as well.

A pending code is simply a fancy word that most tools use to say, hey, there is a potential problem, if it happens again, we are turning the MIL on.

A DTC is a Diagnostic Trouble Code, like P0300.

A normal reading would be .2v to .8v, indicating a good lean to rich cycle. If it is, say .1 to .5, then it is lean biased, as it will never read rich, which will cause a problem. You can have it the same way rich .5v to .9v or so, and it will throw a high voltage O2 code.

Your catalyst monitor will not run if the second O2 is screwed up, or if you have not been cruising on the highway, because that is how the PCM determines if the cat is still good.

Glitches do occur for a reason, that is why the PCM will not turn the MIL on unless it happens twice, otherwise your MIL would turn on randomly, and you may never find the actual problem. Only time the MIL comes on immediately is if emissions exceed 150% FTP limits. In that case it blinks when it happens, and goes solid on once it stops.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowcivic2k &raquo;</TD></TR><TR><TD CLASS="quote">I know you have a obd2 tool, im just saying that you can uncover a one trip fault with a paperclip as well.

A pending code is simply a fancy word that most tools use to say, hey, there is a potential problem, if it happens again, we are turning the MIL on.

A DTC is a Diagnostic Trouble Code, like P0300.

A normal reading would be .2v to .8v, indicating a good lean to rich cycle. If it is, say .1 to .5, then it is lean biased, as it will never read rich, which will cause a problem. You can have it the same way rich .5v to .9v or so, and it will throw a high voltage O2 code.

Your catalyst monitor will not run if the second O2 is screwed up, or if you have not been cruising on the highway, because that is how the PCM determines if the cat is still good.

Glitches do occur for a reason, that is why the PCM will not turn the MIL on unless it happens twice, otherwise your MIL would turn on randomly, and you may never find the actual problem. Only time the MIL comes on immediately is if emissions exceed 150% FTP limits. In that case it blinks when it happens, and goes solid on once it stops.</TD></TR></TABLE>

Alright, but I shouldn't actually care about this monitor, should I? I mean the secondary O2 sensor (from what I understand) doesn't make fuel trim modifications, it only modifies emissions. And since '96-'00 cars in NY can pass with up to two I/M monitors not ready, is there any reason for me to care since it's just the one since it's not even throwing a CEL?

And since it ran a .4, it's lean biased? So you're saying it will never read anything but lean? i don't get it, what's optimal then, 4.5v? How can you tell a working O2 from a "bad and biased" one?

Back in February the last owner said they broke the secondary O2 when putting a new cat back on - and he had to pay 90 bucks for a replacement - could it be possible if he bought a denso or something instead of a Toyota OEM that it's not gonna be right?

MatterMatt

Alright, but I shouldn't actually care about this monitor, should I? I mean the secondary O2 sensor (from what I understand) doesn't make fuel trim modifications, it only modifies emissions. And since '96-'00 cars in NY can pass with up to two I/M monitors not ready, is there any reason for me to care since it's just the one since it's not even throwing a CEL?


The secondary is used to trim the output of the primary for precise A:F ratio control and to determine catalyst efficiency. Fuel trim affects emissions, i.e. too rich will increase HC emissions, possible fuel burning in the cat causing damage, so on. Basically, there is a correlation between fuel trim and emissions.

To pass an OBD I/M Test the minimum number of Readiness checks need to be complete and the MIL/check engine light must be off. If your light is off and you have enough readiness checks completed, you will pass. Just as long as you have the code cleared it sounds like you will be ok for the test, but in the future.....

I totally forgot to mention the 2 trip bypass by jumping the SCS connector. That will make any temporary/pending DTCs go straight to a permanent DTC with MIL on.

slowcivic2k

Because a voltmeter does not graph the output voltage, the best way to view it is with the scan tool/graphing meter driving down the road. Depending on the refresh rate of the meter, it could show the .1 to 1.0v fluctuation like it should, but if your meter is slow, it will read from .45 to around .6v all the time, because you meter will average the two readings.

The second O2 is a slower response sensor used to determine if the catalyst is doing its job. This sensor does not make any fuel trim adjustments, its simply there to monitor the catalyst. It's reading is modified because of the catalyzed exhaust, so its output for fuel trim adjustment is useless, and would result in poor fuel adjustment, which is why the fuel trim O2 sensor is upstream of the cat.

Most inspection stations in PA will make sure the catalyst monitor has run and passed, if not they will send you back out and tell you to come back tomarrow.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by slowcivic2k &raquo;</TD></TR><TR><TD CLASS="quote">Because a voltmeter does not graph the output voltage, the best way to view it is with the scan tool/graphing meter driving down the road. Depending on the refresh rate of the meter, it could show the .1 to 1.0v fluctuation like it should, but if your meter is slow, it will read from .45 to around .6v all the time, because you meter will average the two readings.

The second O2 is a slower response sensor used to determine if the catalyst is doing its job. This sensor does not make any fuel trim adjustments, its simply there to monitor the catalyst. It's reading is modified because of the catalyzed exhaust, so its output for fuel trim adjustment is useless, and would result in poor fuel adjustment, which is why the fuel trim O2 sensor is upstream of the cat.

Most inspection stations in PA will make sure the catalyst monitor has run and passed, if not they will send you back out and tell you to come back tomarrow.</TD></TR></TABLE>

O, IC, in NY it's different, you can have up to two incomplete monitors - it doesn't matter which, that and you can't be throwing a CEL.

I'll take it for a drive tomorrow and see how it reads.

Does the catalyst system usually take longer than the other monitors to ready? It seems like it does.

If it throws another CEL I'll replace the secondary O2...or should I replace the primary b/c that's what the code said?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MatterMatt &raquo;</TD></TR><TR><TD CLASS="quote">Alright, but I shouldn't actually care about this monitor, should I? I mean the secondary O2 sensor (from what I understand) doesn't make fuel trim modifications, it only modifies emissions. And since '96-'00 cars in NY can pass with up to two I/M monitors not ready, is there any reason for me to care since it's just the one since it's not even throwing a CEL?


The secondary is used to trim the output of the primary for precise A:F ratio control and to determine catalyst efficiency. Fuel trim affects emissions, i.e. too rich will increase HC emissions, possible fuel burning in the cat causing damage, so on. Basically, there is a correlation between fuel trim and emissions.

To pass an OBD I/M Test the minimum number of Readiness checks need to be complete and the MIL/check engine light must be off. If your light is off and you have enough readiness checks completed, you will pass. Just as long as you have the code cleared it sounds like you will be ok for the test, but in the future.....

I totally forgot to mention the 2 trip bypass by jumping the SCS connector. That will make any temporary/pending DTCs go straight to a permanent DTC with MIL on.


</TD></TR></TABLE>

Gotcha. So I'll replace the O2 if it comes on again. I'll check it tomorrow & see how it's reading.

slowcivic2k

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Syndacate &raquo;</TD></TR><TR><TD CLASS="quote">

O, IC, in NY it's different, you can have up to two incomplete monitors - it doesn't matter which, that and you can't be throwing a CEL.

Okay, just had to make sure.

I'll take it for a drive tomorrow and see how it reads.

Does the catalyst system usually take longer than the other monitors to ready? It seems like it does.

It can take a while for it to run, if you spend like 15 mins on the highway, it should run, since the cat will be plenty hot and working the way it should.

The poor primary O2 sensor readings could have suspended the secondary O2's ability to monitor the cat, since it will run rich if the primary is screwed up, which would make the cat fail if the test were to run because of excess fuel.


If it throws another CEL I'll replace the secondary O2...or should I replace the primary b/c that's what the code said?

If the primary O2 is what the code is for, that is where your problem is. Replace that one if is doesn't come out good.

</TD></TR></TABLE>

MatterMatt

The secondary sensors primary function is to monitor catalyst efficiency. I forgot to put that SOME vehicles use the secondary to trim the primary signal. Short Term Fuel trim is based on primary 02 sensor input, but that correction constantly varies as the signals from both sensors vary. I think that the secondary is used to trim the primary signal only on some newer Honda vehicles, possibly just the ones with AF ratio sensors/UEGOs for the primary and conventional o2 sensors for the secondary. I'm sorry, that probably has nothing to do with the Tercel. For this application we will just say it monitors catalyst efficiency.

And yeah, if it is a primary code you should replace the primary if it comes out bad.

slowcivic2k

Yep, the newer Honda cars that use the Air Fuel Sensors (functions like a wideband) use the secondary O2 as well to trim fuel/control emissions, since it can actually meter AFR, not just O2.

Syndacate

Got it, I'll bump the thread if it comes back in the next couple of days - if it comes on in a week or something I'll just replace the primary O2.

So when I check the voltage at the O2 through the OBD-II scanner it should be all over the place? It has a graphing function so I can graph it out if I keep it on while I drive - so what should the graph look like, all linear and close to the center, or all over the place? Or just as long as it's not holding high or low?

King V

It should look like a sine wave, lowest point should be like .1 or .2 volts, highest should be .8 or .9, swinging at a regular rate. Thats IF your heater circuit isnt fubar.

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 200kCivicSI &raquo;</TD></TR><TR><TD CLASS="quote">It should look like a sine wave, lowest point should be like .1 or .2 volts, highest should be .8 or .9, swinging at a regular rate. Thats IF your heater circuit isnt fubar.</TD></TR></TABLE>

Ah, I C, thank you.

Syndacate

Okay, so I ran the O2 sensor test today while I was driving, and I'm a bit confused at the results I got:

First off, O2 Bank1 Sensor2 (I'm assuming that's my secondary O2 sensor) says "O2 Bank1 Sensor 2: No Data Retrieved For This SEnsor"

Ahh...does that mean it's not reading my secondary O2? It has to be b/c I'm not throwing a CEL.

Under O2 Bank1 Sensor1 it says:
Lo V for Switch
MAX: -----(v)?
MEAS: 0.400(v)
MIN: -----(v)
MOD: $10

Hi V for Switch
MAX: -----(V)?
MEAS: 0.550(v)
MIN: -----(v)
MOD: $10

I have no idea what the hell that means, it's like it's reading a high and a low, also note those numbers are 100% static, they AREN'T CHANGING AT ALL.

As far as I/M Monitors go, both the O2 monitor, and O2 heater monitor both read "OK"

The only INC is the catalyst efficiency monitor.

I also checked and I have a pending code:
The same P0130:
O2 Sensor
Circuuit Malfunction
(Bank1 Sensor 1)

Normally this would tell somebody to change out the primary O2 sensor..but it seems as though it's not pulling any data on the secondary O2 sensor. No hard codes though. And no secondary O2 sensor codes.

I'm 110% stuck here.

Any help would be greatly appreciated.

O2 sensor for this car is $96 and it's a beater but it's gotta but I really don't wanna drop money into it .

MatterMatt

I think, but I am not sure, that Lo V for Switch translates to Low Voltage reading and Hi V for Switch means High voltage reading. If that is what those mean, the lowest voltage is .4 and the highest is .55, it is stagnant and will need to be replaced. I very well could be wrong because the scan tool I use is much different than yours.