TC21

PLEASE HELP! I've tried searching, but to no avail...

I drive a 1998 Civic DX Hatch, manual. My buddy helped my hack my ECU and we found it was throwing a code 41, which is a Primary Oxygen Sensor Heater malfunction.

Some background:
I have been driving this car for less than a year and it has been running great. The other day my CEL came on and my car died when I came to a stop on the road. It doesn't die every time, more like 20% of the time I come to a stop now.

Question #1 - Does a primary oxygen sensor malfunction normally cause the car to idle low when stopped and cause it to die?
Question #2 - Is the root of my problem something else, like a vacuum leak or maybe a fried ECU perhaps? Can moisture under the hood cause this (there's been alot of rain)?
Question #3 - If I do replace my O2 sensor, I've read I should avoid aftermarket and go straight for OEM. What brands are suggested/need to be avoided?

Thanks again for all your help, I LOVE HONDA-TECH!


Modified by TC21 at 7:17 AM 7/23/2007

TC21

Please help me guys!!

Syndacate

PM Frank_2.0L - he sells Denso (good company for O2 sensors) O2 sensors for 62 shipped for one that plugs into the harness, or 31 shipped for the universal (you have to crimp/solder it to the harness and chop off the plug).

I say get the plug, but you can save ~60 bux by going universal.

He has catalytic converter O2's (secondary) and header O2's (primary).

https://honda-tech.com/zerouser...47058

I just had the same exact code and at a different point I threw a 45.

It was the O2 sensor - I replaced both - no problem after ~1000 miles at least.

#1: It doesn't NORMALLY, but I HAVE seen it happen.
#2: No, a vacuum leak is annoying and will give you a high idle, but it won't make you throw an O2 sensor heater code.
#3: Replace it - take it from there.

EDIT:
Actually, pull fuse 15 and make sure it's not blown. If it's not blown - get a new primary O2 - I was shopping around for awhile for an O2 for my '97 EX - Frank_2.0L has the best deal at 62 shipped for a plug in one.

Fuse 15 on the underdash fusebox:
Second Row Down
Fifth Column From the Left - 7.5a fuse.



Don't forget to count the "spare fuse" as #1 - it's the one that says "alternator sp fuse"

If that's not blown - new O2 sensor. Your speedometer won't work if it's blown, but better safe than sorry.

ru7

My car didnt start and put code 41 also. It was the fuse (blown).

Syndacate

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ru7 &raquo;</TD></TR><TR><TD CLASS="quote">My car didnt start and put code 41 also. It was the fuse (blown). </TD></TR></TABLE>

Ah, okay. Blah.

Okay, your battery is probably dead.

Reason being:
That fuse controls:
- Primary O2 sensor heater
- Secondary O2 sensor heater
- Evap Purge System
- Vehicle Speed Sensor
- Alternator Switch

So if there's a short in that fuse it'll stop all those things - BUT - it would throw a code: 20 - ELD (electronic load detector) - and according to you it's not - which is VERY weird to have an electrical surge and the ELD not read it.

Replace the fuse and jump it. Don't jump it with a booster pack, jump it with a running vehicle, then leave it on there for like ~5 or 10 minutes. Remove the jumper cables and let it idle for a bit and rev it a bit - keep the RPM up a bit.

If the alternator and switch are functioning properly it will continue to charge - if it dies out after revving it a bit - the alternator isn't charging. If it pops that fuse again, and there's still no code 20, it's possible your fuse box (the ELD) is bad - if it pops again AND it throws a code 20, then you have a short - most likely in the secondary O2 or VSS wiring - the alternator wiring is also a possibility, but seeing as you threw a code 41, I'd replace BOTH O2 sensors first - and see where you are from there.

Once that fuse blows the alternator switch won't kick on - so the alternator won't charge the battery, so the reason for it not starting is probably just a dead battery.

EDIT:
PS: To check your codes w/o going to autozone or starting your car go here:
https://honda-tech.com/zerothread/1901557

ru7

Not true in my case...

We were puting ITR cluster in EK4. We forgot to unplug the battery so we made a short circuit. We didnt know the fuses has gone...

After we put it together we coudnt start the car (Engine check). The code was #41. We started to check fuses and after changing alternator fuse (7,5 amp), the car started right up...

Wierd... The battery was fine.