Okay, if you were like me and not wise to all of the 'know-how' regarding Check Engine Light (CEL) codes, Malfunction Indicator Light (MIL), Diagnostic Trouble Codes (DTC) and the role of ODB-II / ODBII...........WELL THEN THIS IS FOR YOU
My first post here was regarding a Check Engine Light (CEL), and I'm pretty sure that's how a good lot of you guys and gals introduced yourselves as well. I searched and was overwhelmed by a ton of information that only confused me more. I promised myself that I would compile as much information as I could gather and submit it to you guys in hopes of helping others.
I just hope that the MODS recognize a need for this in our Accord Forum and sticky this information in some shape or form so that our fellow Accord owners will have a quick reference for much needed and often requested information......so please vote
Here We Go!!
There is a misconception that all 1996 and later model cars HAVE to be diagnosed by a dealer or by using the ODB-II tool.....This is not the case!!
You can do this yourself by utilizing the ODB-II connector located under the drivers side of the dash (see picture below) and inserting a paperclip as shown:
The following is some general info on the ODB-II / ODBII system that is universal on all models after 1996:
The folllowing question and answer section is courtesy of Overboost.com..........don't worry the codes will come later.
First Thing's First: What Is OBD-II?
The term "OBD-II" can almost be categorized as a set of standards, and they're all gone over in great detail in the SAE On-Board Diagnostics for Light and Medium Duty Vehicles Standards Manual. OBD-II is really an international standard that covers everything from diagnostic codes to the shape of the data port connector where the codes are scanned. Prior to OBD-II, automakers invented their own methods for getting diagnostic information from on-board computers. Getting codes required the ignition key to be turned on-off-on-off-on, and then decoding the "Morse Code" blinks from the CHECK ENGINE light. "Code 13" would be one long blink for the 1 and three short blinks for the 3; a code 23 would be two long blinks for the 2 and three short blinks for the 3. On Hondas you had to pull up the carpet to see the ECM, and the ECM had an LED that would blink out a diagnostic code where 13 blinks would be a code 13... if you have several codes, be prepared to sit there a while counting blinks and hope you don't miss one and have to start over! With OBD-II, all codes are the same and the data port where you read them is the same (three feet from the driver and accessible without tools).
Does a CHECK ENGINE Light Necessarily Mean Power is Lost?
The short answer is NO. OBD-II conventions indicate that the major reason to set the CHECK ENGINE light (or Malfunction Indicator Lamp or MIL) is for a problem that immediately affects emissions. Removing the oxygen sensor downstream of the catalytic converter will set the MIL, but this sensor has absolutely zero to do with fuel, spark and boost. As far as the ECM is concerned it means your catalytic converter isn't doing its job of grinding up exhaust particles. Some engine faults will set the MIL immediately and some have to be recurring, so theoretically you could have a problem, no MIL and a power loss. The system's not perfect.
What Exactly is "Limp Home" Mode?
This is the portion of the OBD-II standards that makes cars more reliable. In the old days, if your MAF became disconnected the engine might stall or it might still run at 100 percent fuel delivery. On OBD-II cars, a disconnected MAF will cause the computer to keep the engine running using data from RPM, throttle position and MAP sensor. OBD-II computers also have big brains. If a coolant temp sensor reads 200 degrees F one minute and drops to –30 the next, the ECM will realize something is wrong and remove its output from the fuel and spark decision tree. (In this case, the ECM will base its decisions on a coolant temp of 176 degrees F.) Here's something else neat that owners of late-model VWs and Audis can appreciate. If one cylinder is misfiring excessively, raw fuel is dumped into the exhaust stream and can cause the catalytic converter to overheat. OBD-II ECMs can detect this and will temporarily shut off the fuel injector to the offending cylinder.
Can Aftermarket Mods Cause a "Limp Mode" Situation?
They can and do, but not usually experienced from a proper bolt-on part such as an exhaust or down pipe. Although some exhaust systems will set of the Check Engine Light because some down pipes don't retain enough heat to keep the catalytic converter at operating temp. The basic rule of thumb when dealing with an OBD-II system is to not screw with sensor data.
Some Quick Jargon
So, what do the codes look like? Their proper name being: Diagnostic Trouble Code or DTC, which is a five-digit alphanumeric string. The first character is a letter that indicates the trouble group; the second character indicates if the code is an OBD-II code or proprietary; the third character indicates the vehicle sub-system and the last two characters are the fault number.
There are some "generic" DTCs. This is because each generic DTC could have numerous DTCs under it. This is to make sure that standard OBD conventions can suit all vehicles. For example, ECT sensor, P0115. The exact verbiage of this error is "Engine Coolant Temperature Circuit Malfunction." P0116 is "Engine Coolant Temperature Circuit Range/Performance Problem." There are no fewer than five DTCs for the coolant temp sensor alone, but not all cars will use all of them. There are 37 separate codes for oxygen sensors; some cars have dual exhausts and use two front and two rear sensors. Some might use three sensors per pipe. The OBD conventions cover all permutations. Also, at times a single failed sensor can cause a litany of DTCs; a bad oxgyen sensor can give you a P0130, P0131, and P0133, and simply replacing the sensor would fix all three. This is one of those examples when the ECM takes its job a little too seriously and throws the book at you.
What Are the Limp Modes and What Causes Them?
There are some proprietary failures that aren't listed in the table below, but the major OBD-II conventions are listed and represent the bulk of what you'll need to know. Bad or missing data from one of the following sensors will cause the ECM to go into a "limp home" mode:
Mass Air Flow (MAF), Mass Air Sensor (MAS), Vein Air Flow (VAF), Manifold Absolute Pressure (MAP)
ECM will use throttle position and engine RPM for basic fuel delivery function; disables active idle control. Generic DTC: P0100
Intake Air Temperature (IAT) sensor
ECM will assume air temp is a constant 25 degrees C/77 degrees F. Generic DTC: P0110
Throttle Position Sensor (TPS)
Disables temporary fuel enrichment on acceleration (can cause hesitation/stalling). Generic DTC: P0120
Engine Coolant Temperature (ECT) sensor
ECM will assume coolant temp is 80 degrees C/176 degrees F. Generic DTC: P0115
Camshaft Position (CMP) sensor
On a four-cylinder engine, runs injectors in a 1-3-4-2 firing order with irregular timing. If no signal is present, shuts of fuel supply after four seconds. Generic DTC: P0340
Barometric pressure sensor (BARO)
Assumes that atmospheric air pressure is sea level (101 kPa/30 inches Hg). Generic DTC: P0105
Crankshaft Flux (knock) sensor (CKF)
Switches ignition timing profile from high-octane to low-octane mode. Most factory turbo cars will go into a lower-boost mode too. Generic DTC: P0325
Shuts off fuel to the misfiring cylinder. Some ECMs use crank speed variations and some ECMs that use ultra fast oxygen sensors can use the sensor's profile to figure out which cylinder is misfiring. Generic DTC: P0300
Exhaust Gas Oxygen (EGO) Sensor – Front
Does not use EGO sensor to provide corrected fuel delivery; ECM goes straight from lookup tables. Generic DTC: P0130
Exhaust Gas Oxygen (EGO) Sensor – Rear
Although this failure won't cause a power loss, but will cause the MIL to illuminate and we're compelled to discuss it. The front sensor is used for fuel trim correction but the rear sensor's data is almost totally ignored by the ECM. As long as the rear sensor's cross counts are fewer than the front sensor's, the ECM assumes the catalytic converter is working normally. Generic DTC: P0130
Turbocharger wastegate actuator
If the ECM decides that boost pressure is too high (through excessive air flowing through the MAF or by a more direct measurement with a MAP) then fuel is cut until boost drops back down. Generic DTC: P0243
--Credit where credit is due...again all of the info above within the smileys is courtesy of Overboost.com--
67 Catalyst system Efficiency Below Threshold malfunctioning or defective catalyst system
70 Automatic Transmission malfunction with the automatic transmission controls
71 Cylinder 1 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire
72 Cylinder 2 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire
73 Cylinder 3 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire
74 Cylinder 4 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire
80 Exhaust Gas Recirculation insufficient flow detected
86 ECT Sensor (Engine Coolant Temperature) circuit range / performance problem
90 Evaporative Emission Control System leak detected in the fuel tank area
91 Fuel Tank Pressure Sensor low input
92 Evaporative Emission Control System insufficient purge flow
All the info listed within the 'thumbs-up' section above were compiled with scattered information found on the internet and then put together in Excel by me ---> "MuthaFodder". A copy of the Excel file can be sent over AIM or maybe an email if requested, it doesn't come out that well here in this thread.......courtesy of me and a few hours of my life fellas.
This info should without a doubt cover all 1998-2002 / 98-02 / 1998 1999 2000 2001 2002 Accords. The resetting of the ECU process will likely work for other models as well though.
Now, that you now know all about codes, you must understand your car will continue to operate poorly since the CEL was set off and the ECU (Electronic Control Unit) has not yet been reset to clear the codes.
The code may have been set off by an anomally that will likely not happen again (low oil level, etc) or you may have a whole slew of things wrong with it. Regardless even after replacing and repairing the parts in question, your car may not operate normally until you reset your ECU and clear the codes from memory.
** Info for resetting the ECU or clearing the ECU / CEL check engine light codes:
Remove the 7.5 amp fuse labeled "Clock Back-UP" on the PASSENGER'S side, it is the number 13 fuse on the box, for at least 10 seconds. Do not undo the negative battery cable.....you don't have too. **
What I would suggest to do after getting a CEL code:
First, determine and record the code by watching the the CEL flash.
You will get a series of long and then short flashes. A long flash is valued at 10 points and a short flash is valued at 1 point. You may have more than one code and this is displayed by a long pause after the short flashes. If a second code is present, the long flashes will begin again after the long pause. Add up the 'point' value of each code to get a number of 1-92. You may want to watch the cycle of code(s) a couple of times to ensure you can record all of the codes.
Next, I would reset the ECU by the process detailed above within this reply and in bold. After the ECU has been reset and the codes cleared, I would go for a test drive to ensure that the thrown code was not an anomally........I would do this only if after starting my engine and the Check Engine Light (CEL) did not reappear immediately. Don't give it hell, just drive around seeing if the CEL will repeat itself.
If the CEL does reappear immediately, make sure you are resetting the ECU properly (again see above process). If it still reappears, you have something wrong, be it little or big, a problem is present....that my friend is up to you to figure out....good luck.
If you hadn't been kind in showing patience with me and a giving me a warm welcome, I may never have been inspired to do this.
...and please anyone who has any general Accord info relating to repairs, common glitches / fixes, more codes for other model Accords, etc....please go ahead and post it within this thread for reference.
Bumper .....Sticky! Come on make it a sticky!!! u know u want tooo!!!!
1994 Accord 2.2 LX
149k miles [url="http://www.honda-tech.com/zerothread?id=1698425"]http://www.honda-tech.com/zerothread?id=1698425[/url]
For Sale: TYC Altezza Taillights Euro Red Mint! 70 Shipped [B]obo[/B] email me [email]Accordisslow@gmail.com[/email]
I am the original owner of a 2001 Honda Accord bought in Canada.
The CEL came on one day and I was trying to figure out how to determine the code without a Scan tool.
I determined from the internet that one shorts out pins 8 and 13 on the OBD II connector, then turns the ignition on and counts the flashes, then looks up the code on the table.
Well, this does not work as there are no wires going to these pins!
I am 99.9% sure I have read the OBD pin numbers/orientation correctly.
Since then, the CEL has gone off. I suspect I overfilled the gas tank and this caused a temporary CEL fault.
For the future, any suggestions how to get the OBD codes? Local parts stores do not offer free scan services..
Greetings to everyone and thanks to MF for posting and to TouringAccord and GhostAccord for the additional info. Here's a model-specific question that I hope you can assist with:
On a '94 Accord EX 4 cylinder AT, I've got the CEL on steady (it does not even blink when I jump the codes), and I've got a blinking D4 light throwing code 14. In various posts I've seen that Transmission DTC 14 can mean either "open of short in FAS Wire, or faulty PGM-FI control unit" OR "Linear (line pressure control) solenoid open or shorted."
So my question is, which one is it for my particular car: FAS Wire/PGM-FI or line pressure control solenoid?
The symptoms (in case it will help) are slight jerk followed by rough idle upon reaching a speed of about 5mph, and then at high speeds an occasional "trembling" shift. I've already changed out the VSS (that cleared a DTC 4 that was also showing) and I have changed out the transmission fluid and I've swapped the TCU.
Can anyone help me with this.... buy radioshack part #271-1125
connect two of them together at one end, connect that connection to D15. One open end to D10 the other to D11. this shows 2.5V to the input to the ECU, which means no CEL. "
Does it work for P0453 and does anyone have the pinouts for a 96 accord ECU so I can verify. I have a 96 w/o a fuel tank high pressure sensor. It may have newer ECU in it. What years will this work with
I have a 1998 Honda Accord LX 4 cyl with about 130000 miles. The light to the AC control unit would go off and on while driving. When the lights go off, the AC nor the heater would work. However, when the lights to the AC control unit would come on, everything would work fine. I read on another thread that you can run a self diagnostics by holding the recirculation button and the recirculation light would start blinking out codes. I was wondering if you would use the same method to read OBD-II for those blinking light and determine the error code. Thanks
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