How To: Diagnosing Your Check Engine Light

[absntmnd69]

Is your CEL on? Well I know that you don't want to go to the dealer to pay $90 just to tell you why. Well, I have a way for you to check and turn it off yourself.

Items Needed:
A piece of wire with both ends stripped
Common Sense

1. Get a small piece of wire like so:
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy003.jpg

2. Pull the first Service Connector behind the center console:
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy001.jpg
The connector should look like this:
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy008.jpg

3. Take your wire and stick it in the ends of the connector like so:
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy009.jpg

4. Now turn the key to the"ON" position and watch the CEL light for the code.
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy010.jpg
The Check Engine Light can indicate any number of simultaneous componet problems by blinking seperate codes, one after another. Problem Codes 1-9 are indicated by individual short blinks. Problem codes 10-43 are indicated by a series of long and short blinks. The number of long blinks equals the first digit, the number of short blinks equals the second digit.

4. Remove the jumper wire when finished pulling the codes

5. When trouble shooting is completed, perform the following procedures:
-Reset the ECU by removing the 10A Clock/ Radio fuse in the underhood fuse block:
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy012.jpg
http://i59.photobucket.com/albums/g320/absntmnd69/tutorials/diy011.jpg

-Reset your radio presets and your clock.

Here are the DTC's (Diagnostic Trouble Code):
0-Engine Control Module (ECM)
1- Heated Oxygen Sensor (HO2S)
3- Manifold Absolute Pressure (MAP Sensor)
4- Cranshaft Position (CKP Sensor)
5- Manifold Absolute Pressure (MAP Sensor)
6- Engine Coolant Temperature (ECT Sensor)
7- Throttle Position (TP Sensor)
8- Top Dead Center Position (TDC Sensor)
9- No. 1 Cylinder Position (CYP Sensor)
10- Intake Air Temperature (IAT Sensor)
12- Exhaust Gas Recirculation ( EGR Valve Lift Sensor)
13- Barometric Pressure ( BARO Sensor)
14- Idle Air Control ( IAC Valve)
15- Ignition Output Signal
16- Fuel Injector
17- Vehicle Speed Sensor (VSS)
20- Electrical Load Detector (ELD)
21- Variable Valve Timing & Valve Lift Electronic Control (VTEC) Solenoid Valve
22-Variable Valve Timing & Valve Lift Electronic Control (VTEC) Pressure Swtich
23- Knock Sensor (KS) *Except F22 engines*
41- Heated Oxygen Sensor (HO2S) Heater
43- Fuel Supply System

Thats it. I've done this plenty of times and have never had a problem. Thanks for reading.

-Alex

[Showaski39]

So if the CEL blinks once that means its the 02 sensor?

[absntmnd69]

if its a long blink yes

[Prelude13]

Excellent tutorial.
Thanks Alex!

[dakilla4ever]

so if its a code 43 what do you do? Change the entire fuel system out?

[bLatantLude22]

wouldnt a single long blink mean #10 not 1.. since 1-9 are indicated by short blinks?
this is for all ludes im guessing?
my CEL came on yesterday so this will be very much help.. thanks a lot.

[absntmnd69]

code 43 is the fuel pump or injectors. yes sorry about that. no this isnt for all ludes. obd 1 (92-96) ludes only. obd 2 can be diagnosed by advance or auto zone

[BadMofo]

code 43 is the fuel pump or injectors. yes sorry about that. no this isnt for all ludes. obd 1 (92-96) ludes only. obd 2 can be diagnosed by advance or auto zone

I have an obd 2 97 prelude type sh... you can diagnose the cel in the same way on mine. Diagnostic plug is on the passenger side of the center console, behind a pull-away piece of carpet, only difference is the plug only has 2 pins instead of three. Same technique though, jump the 2 pins together, and turn the key to on. This also works for the ATTS light on type SH preludes, but the atts codes are unique to the atts computer, so you have to find the list of codes for the atts. Also, the atts light comes on by default if the CEL comes on, or if the ABS light comes on, so if your atts light is on with the CEL or ABS light, then you should troubleshoot them first.

[96jdmh22a]

my cel doesnt come on until i have been driving for a while.
so would it still work even though its not on at start up?

[twokexlv6coupe]

yes it should still work

[vish]

OK so my car died WHILE I was driving down the road yesterday about 3 times... '93 2.2L F22A engine. The check engine light doesn't come on until the car dies. And if the car is still "hot" the engine cranks but won't start until it's cooled down a bit. I'm guessing it's the ignitor or the fuel filter.. but my ignitor I'm sure is ok since I had it replaced about 15k miles ago. Spark plugs ok, spark ok, distributor ok. It can't be the fuel pump because if it is my car wouldn't even be starting up.

I've tried doing this test to see what the CEL was about, I'm actually doing it right now in my car while im on my laptop... the CEL doesnt blink or anything to tell me what's wrong. ????

[BadMofo]

OK so my car died WHILE I was driving down the road yesterday about 3 times... '93 2.2L F22A engine. The check engine light doesn't come on until the car dies. And if the car is still "hot" the engine cranks but won't start until it's cooled down a bit. I'm guessing it's the ignitor or the fuel filter.. but my ignitor I'm sure is ok since I had it replaced about 15k miles ago. Spark plugs ok, spark ok, distributor ok. It can't be the fuel pump because if it is my car wouldn't even be starting up.

I've tried doing this test to see what the CEL was about, I'm actually doing it right now in my car while im on my laptop... the CEL doesnt blink or anything to tell me what's wrong. ????


You don't have any error codes, the only reason your CEL is coming on is your CEL is always gonna come on with your key turned to the on position and your engine not running. When your engine stalls out your CEL comes on, along with some other lights too some times (oil pressure etc...). Sounds like whatever is causing your engine to stall out isn't causing any CEL errors... at least none that your ECU is committing to memory....

[HondaNeedsBoost]

would that blue plug maybe have 2 slots instead of 3? cuz i can not fins a blue one with 3...just 2...the only one with just 3 is grey and about inch and a half long? help pleaze

[JOSE_LUDE]

So if it dose not blink its the ecu ??
Because mine when I turn it to "ON" all the lights turn on and then the engine light is the only one that goes away in about a second. Then when I turn the engine ON they all turn OFF and then my Check engine turns ON. ??????

[hojemwod]

would that blue plug maybe have 2 slots instead of 3? cuz i can not fins a blue one with 3...just 2...the only one with just 3 is grey and about inch and a half long? help pleaze

but I found a different website (they wouldnt let me post it here) that shows the blue 2P connector as the one to use...so the blue one it is...it also says do not jump the 3P connector, which is grey(on mine)

[93H23A1]

but I found a different website (they wouldnt let me post it here) that shows the blue 2P connector as the one to use...so the blue one it is...it also says do not jump the 3P connector, which is grey(on mine)
yeah it's the one with 2 cuz i had to check my abs light and it was the one with two

[93H23A1]

its the connector with 2 not 3:mad:

[hojemwod]

Are these the same codes for the green blinking transmission light?

[93H23A1]

yeah your green light SHOULD blink instead of the CEL

[hojemwod]

they both blink lol, im getting a few codes from the tranny(1,2,3,4,8,14,15) and one from the CEL(17), any advice? thanks

[carstuffer]

great job on the troubleshooting. it was really helpful with the instructions and the pics as well. they go hand in hand pretty good. keep it up! =D

[lowballer]

so im to use the blue 2 slot connector from the passenger side of the center not the gray 3 slot connector from the driverside???

[LudeLove99]

I don't have the same problem but I think I have a similar one.. First of all I have a 99' prelude 140k mi and my maintence required just turned yellow. Does that mean that the car has problems ? Or if not, how do I take it off?

[hojemwod]

so im to use the blue 2 slot connector from the passenger side of the center not the gray 3 slot connector from the driverside???

correct...download the 92-96 service manual from the 4th gen resource guide, it tells you the cel codes and the d4 light codes and how to fix them (starts
around page 14-36)

[LayiNSparxX]

Hey how do i check the light in my CB7? i i have OBD1

[92_prelude]

This is awesome.....STICKY!!!!!!!

[mcimo]

My light has been on since I got my car. So, yesterday I opened up my dash and took out the light bulb. Poof! No more CEL for me!! :tongue:

[BadMofo]

My light has been on since I got my car. So, yesterday I opened up my dash and took out the light bulb. Poof! No more CEL for me!! :tongue:

Did you check it to see what was wrong with it first? Lol, that light is normally there for a reason.. it usually means to "check your engine".

[mcimo]

LOL! I used to have an aftermarket exhaust system (before the stupid popo pulled me over, and my parents made me remove it) that probably messed with the O2 sensor. I've had the code pulled and I'm pretty sure thats what I was, but the light still stayed on. I figured if its going to always be on, I wouldn't know if there actually was something wrong with it anyways, so I just pulled the bulb. My engine runs just fine as it is, so I'm not too worried about it. At least now I don't have to look at it anymore! Hahaha. Oh yeah can my car pass inspection without the light in, or will I have to put it back in before my next inspection?

[BadMofo]

well if it's your o2 sensor, and that is whats causing the code, then your engine is not running just fine, even if it seems like it is. go buy new o2 sensors, get denso's... they're only like 30 bucks ithink and they come with a direct fit wire harness so they are plug n play. trust me man, replace your o2 sensors, and then you don't have to pull your bulb to not see that CEL anymore... if your o2 sensors aren't working right, then your motor is either gonna end up running too rich, or too lean, which could be bad for performance, and bad for the life of your motor... so do it right bro...i'm tellin' ya, just because your motor seems tobe runnin' alright... doesn't mean it is.

[snakerb]

WIll this work for the fifth gen as well?

[HondaNeedsBoost]

very nice write up...ive tried this but i never got any results...alwell...my car might just hate me :tongue:

[BadMofo]

WIll this work for the fifth gen as well?

Go here... (http://www.preludezone.com/showpost.php?p=56093&postcount=8)

[ididdy]

If his car is a 96+ then the CEL is probably from a missing cat, now that you have the stock exhaust back on you can just pull the radio fuse out and reset the codes and if all is well the yellow light will be gone.

[BadMofo]

If his car is a 96+ then the CEL is probably from a missing cat, now that you have the stock exhaust back on you can just pull the radio fuse out and reset the codes and if all is well the yellow light will be gone.

Who are you talking to/about? And what makes you think that because a car is a 96+ it has a CEL because of a missing cat??? I have a 97 and my cel was on for a misfire in cylinder 1.... you tellin me that i should just replace my cat and call it a day? =P. Why just guess what's causing the CEL when we are teaching you, right here in this very thread, how to properly diagnose it....

[ididdy]

I was talking to the kid who replaced his aftermarket with exhaust with the stock one and is still throwing a code, the code is still stored he needs to reset the ecu to know if its still there or not.

[Smok3y]

Thanks for The Tutorial. Does it work with All hondas? I own a EK hatch also ...

[BadMofo]

It's probably pretty similar.

[Prelude92]

my car has 2 jumpers.. One is blue the other is gray.. any idea what the gray one is for??

[hojemwod]

my car has 2 jumpers.. One is blue the other is gray.. any idea what the gray one is for??

i beleive they all have 2 jumpers, use the blue one....i forget exactly what the gray is for

[Keeny]

Hi, im a newbie,
I just purchaced a 94 prelude off ebay,
i got it home & the ABS light stays on, so i disconected all sensors cleaned them and the sensor rings put all back together but i dont know how to reset the ABS light to see if ive rectified the problem.. The 4ws light is on too the guy i got the car off said it only started to light up since he put new alloys with wider tyres on the car can i reset the light or do i have to pay a fortune at a Honda garage :biggrin: Cheers Keeny

[twokexlv6coupe]

after pulling my hair out trying to find out what a CEL 65 and 91 were, i found this gem of a chart:


CODE VEHICLE DEFINITION
1 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
Oxygen Sensor "A" (Primary) defective circuit or unplugged / defective sensor

2 86-87 Civic
Oxygen Sensor "B" defective circuit or unplugged / defective sensor

3 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
MAP Sensor (Manifold Absolute Pressure) defective circuit or unplugged / defective sensor

4 88-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
CKP Sensor (Crankshaft Position Sensor) defective circuit or unplugged / defective sensor

5 86-98 Civic*
97-98 CRV
85-98 Prelude
94+ Integra
MAP Sensor (Manifold Absolute Pressure) mechanical problem / disconnected piping
* not 94-95

6 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
ECT Sensor (Engine Coolant Temperature) defective circuit or unplugged / defective sensor

7 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
TP Sensor (Throttle Position) defective circuit or unplugged / defective sensor

8 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
TDC Sensor (Top Dead Center) defective circuit or unplugged / defective sensor

9 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
CYP Sensor (Cylinder) defective circuit or unplugged / defective sensor
* invalid code for throttle body injection Hondas
** invalid code for V6 engines

10 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
IAT Sensor (Intake Air Temperature) defective circuit or unplugged / defective sensor

12 86-98 Civic
85-98 Prelude
94+ Integra
EGR Lift Sensor (Exhaust Gas Recirculation) defective circuit or unplugged / defective sensor
* invalid code for non-equipped EGR valve vehicles

13 86-98 Civic
97-98 CRV
85-98 Prelude
94+ Integra
BARO Sensor (Atmospheric Pressure) defective circuit or unplugged / defective sensor

14 88-98 Civic
97-98 CRV
88-98 Prelude
94+ Integra
IAC Valve (Idle Air Control) defective circuit or unplugged / defective sensor

15 88-95 Civic
88-95 Prelude
94+ Integra
Ignition Output Signal missing or defective ignition output signal

16 88-95 Civic
88-85 Prelude
94+ Integra
Fuel Injector System defective circuit or unplugged / defective fuel injector

17 88-98 Civic
97-98 CRV
88-98 Prelude
94+ Integra
VSS (Vehicle Speed Sensor) defective circuit or unplugged / defective sensor

19 88-95 Civic
94+ Integra
Automatic Transmission Lock Up Control Solenoid Valve defective circuit or unplugged / defective solenoid valve

20 88-98 Civic
97-98 CRV
92-98 Prelude
94+ Integra
Electrical Load Detector defective circuit or unplugged / defective sensor

21 92-95 Civic
93-95 Prelude
94+ Integra
VTEC Solenoid Valve defective circuit or unplugged / defective solenoid valve
* invalid code for non-VTEC engine
** invalid for V6 engine

22 92-98 Civic
93-98 Prelude
94+ Integra
VTEC Oil Pressure Switch defective circuit or unplugged / defective oil pressure switch
* invalid code for non-VTEC engine

23 96-98 Civic
92-98 Prelude
94+ Integra
KS (Knock Sensor) defective circuit or unplugged / defective sensor
* invalid code for V6 engine

30 92-98 Prelude
94+ Integra
Automatic Transmission Signal: "A" / SEAF / SEFA / TMA or TMB defective circuit or unplugged / defective sensor
* invalid code for 1996

31 92-95 Prelude
Automatic Transmission Signal "B" defective circuit or unplugged / defective sensor

41 92-98 Civic
97-98 CRV
90-98 Prelude
94+ Integra
Primary Oxygen Sensor - Heater circuit malfunction

43 92-95 Civic
90-95 Prelude
94+ Integra
Fuel Supply System defective or malfunctioning fuel supply system

45 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
System Too Lean or Too Rich malfunction in the fuel monitoring systems

48 92-98 Civic
94+ Integra
LAF Sensor (Lean Air Fuel) defective circuit or unplugged / defective sensor

54 96-98 Civic
97-98 CRV
94+ Integra
CKF Sensor (Crankshaft Speed Fluctuation) defective circuit or unplugged / defective sensor

61 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Oxygen Sensor, Heated - Sensor 1 (Primary) high voltage, low voltage, or slow response

63 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Oxygen Sensor, Heated - Sensor 2 (Secondary) high voltage, low voltage, or slow response

65 96-98 Civic
97-98 CRV96-98 Prelude
94+ Integra
Oxygen Sensor Heater (Secondary) malfunctioning or defective oxygen sensor heater

67 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Catalyst system Efficiency Below Threshold malfunctioning or defective catalyst system

70 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Automatic Transmission malfunction with the automatic transmission controls

71 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Cylinder 1 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

72 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Cylinder 2 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

73 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Cylinder 3 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

74 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Cylinder 4 Misfire or a Random Misfire a condition is present that is creating a cylinder misfire

80 96-98 Civic
96-98 Prelude
94+ Integra
Exhaust Gas Recirculation insufficient flow detected

86 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
ECT Sensor (Engine Coolant Temperature) circuit range / performance problem

90 96-98 Civic
97-98 Prelude
94+ Integra
Evaporative Emission Control System leak detected in the fuel tank area

91 96-98 Civic
97-98 Prelude
94+ Integra
Fuel Tank Pressure Sensor low input

92 96-98 Civic
97-98 CRV
96-98 Prelude
94+ Integra
Evaporative Emission Control System insufficient purge flow


Courtesy of: http://www.c-speedracing.com/faq/05.php

[SEEKER760]

ur alternater might be going bad or is ur car leaking oil check the distibuter bcuz if its work but getting falty it could turn off bcuz itz to hot that why u have to wait till it cools of then it works. same thing hapened to me. i changed the alternater,distributer,egr valve,nock senser. now my car wont turn off wen its hot but if it does it will turn right back on.