95 YJ 2.5L - Check Engine Light on when starting cold - JeepForum.com
LinkBack Thread Tools
post #1 of 8 Old 02-01-2006, 09:11 AM Thread Starter
Registered User
gary1's Avatar
2000 TJ Wrangler 
Join Date: Mar 2004
Location: NW PA
Posts: 229
95 YJ 2.5L - Check Engine Light on when starting cold

I know I could go to the dealership and have the code read, but I thought maybe somebody could tell me right up front what my problem is.
The Check Engine light comes on when the Jeep starts up cold. After it warms up a little bit the light won't come on when started.
It seems to run good even with the light on. I'm hoping its just a simple sensor, or something along those lines.
Thanx in advance for any response.

gary1 is offline  
Sponsored Links
post #2 of 8 Old 02-01-2006, 09:47 AM
Lighting Guy
Registered User
Join Date: Aug 2005
Location: Ohio
Posts: 52
This is taken from the FAQ pinned at the top:

Self-diagnostic codes can be obtained from your 91-95 YJ by simply inserting the key into the ignition. Turn the key to the on position (when the lights on the dash come on) then off, on, off, and on. It has been said that you need to go through key cycle in less than 5 seconds.
Now that you have cycled the key on, off, on, off, on, the check engine light will begin to flash. One flash a short pause and two flashes indicates a code 12, three flashes, a short pause, and three flashes indicate a code 33. There will longer pauses between codes when there are multiple fault codes.
If your check engine light will not come on it's fairly common that it's because the bulb is burned out. In that case just remove the guage cluster and replace the CEL bulb with the bulb for the seatbelt reminder.

When you determine what codes are stored in the computer you must disconnect the battery for a minute or so after you have completed the repair so that the code will be erased from the computers memory. If you don't do it the motor will still run badly because the computer will still think there is a problem even though the check engine light is not on.

Here are the codes as listed in Chiltons.

11 No crank reference signal at PCM

12 Battery disconnect

13 No change in MAP from start to run

14 MAP sensor voltage too low or too high

15 No vehicle speed (distance) sensor signal

17 Engine is cold too long (thermostat stuck open)

21 O2S stays at center or O2S shorted to voltage

22 ECT sensor voltage too high or too low (engine coolant temperature sensor is faulty)

23 Intake air temp sensor voltage too low or too high

24 Throttle position sensor voltage too high or too low

25 Idle air control motor circuits

27 Injector control circuit

33 Air conditioning clutch relay circuit

34 Speed control solenoid circuit or switch voltage

41 Generator field not switching properly

42 Auto shutdown relay control circuit

44 Battery temp sensor volts out of limits

46 Charging system voltage too high

47 Charging system voltage too low

51 O2S signal stays below center (lean)

52 O2S signal stays above center (rich)

53 Internal PCM failure or PCM failure SPI communiations

54 No cam sync signal at PCM

55 Completion of diagnostic code display

62 PCM failure SPI miles not stored

63 PCM failure EEPROM write denied
Lighting Guy is offline  
post #3 of 8 Old 02-02-2006, 01:38 PM Thread Starter
Registered User
gary1's Avatar
2000 TJ Wrangler 
Join Date: Mar 2004
Location: NW PA
Posts: 229
process you described, and my code is 33 (Air Conditioning Clutch Relay Circuit).
Considering the fact that I don't have AC in my jeep is there something else I should know about this code.
gary1 is offline  
post #4 of 8 Old 02-02-2006, 01:58 PM
Registered User
1995 YJ Wrangler 
Join Date: Nov 2004
Location: central arkansas
Posts: 1,020
something may be screwing with the light or pcm itself, it should come on when started, cold or hot. Does it stay on until it is warmed up? Does it come on while starting warm and just go right off? Also, no don't worry about the code 33.

The YJ is no longer my DD. I have sacrificed all future retirement plans for jeep parts. I'm depending on social security!
blake989 is offline  
post #5 of 8 Old 02-02-2006, 08:08 PM
Registered User
Join Date: May 2005
Posts: 126
i have a 94 2.5 and it use to stumble and the check light was on. after i put the 4.0l throtlle body on i havnt had a problem

I still dont see y the motor mount broke.....it was only 6 feet of air.

94 yj 2.5L-Custom Snorkel, Custom Interior(Spray Paint), 30's in the back, 205's in the front, 9 piece windshield,
jeepmud is offline  
post #6 of 8 Old 02-02-2006, 11:24 PM
Registered User
Join Date: Nov 2005
Location: Finland
Posts: 129
I recently started topic for error code 33, and after some comments we were to come to conlusion that without a/c equipped YJ:s all give that code, because of the open relay for bolt-on a/c. It seems its easier to build a vehicle with wiring for all possible options, then just bolt those options on that the buyer has ordered...

But my YJ gave 12,33,55. I suppose you got those too (although 12 and 55 arent actual trouble meaning codes)?

Could it be that the a/c open relay is somehow pointed for example upwards and its frozen for small snow particles flying when you drive- and then melted into it when engine has warmed up. -- and then giving the code 33.

stock 91YJ from Finland
I said NO to trackbars
finwrangler is offline  
post #7 of 8 Old 02-03-2006, 02:40 PM Thread Starter
Registered User
gary1's Avatar
2000 TJ Wrangler 
Join Date: Mar 2004
Location: NW PA
Posts: 229
My check engine light comes on momentarily when starting the jeep which it should. I doesn't stay on, but when checking the code I did get the 12,33,55 sequence that you mention. I guess for now I'll just assume nothing is wrong.
I runs perfectly, so I don't think it has any effect on anything. It just wondered what might be happening.
Thanx for all the info...
gary1 is offline  
post #8 of 8 Old 02-03-2006, 07:10 PM
95 jeeper
Registered User
1995 YJ Wrangler 
Join Date: Aug 2005
Posts: 77
My check light comes on everytime it rains or is moist out. After I drive for a few minutes and start it again it is always off so ifigure it is a sensor getting a little wet. As long as it goes out and the codes don't change I don't worry about it. My .02
95 jeeper is offline  

Quick Reply

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
Cold Engine Starting Trouble sherrodk YJ Wrangler Technical Forum 15 10-21-2009 10:24 AM
starting trouble; now check engine light (need help) dabrogger TJ Wrangler Technical Forum 1 02-06-2009 01:31 AM
Check Engine Light and cold weather?? Mickeymouse YJ Wrangler Technical Forum 15 01-04-2009 02:52 PM
Check Eng light on after Cold airitnake install sfr119 TJ Wrangler Technical Forum 8 09-17-2008 07:03 AM
Cold Starting Check Engine light woody59 YJ Wrangler Technical Forum 0 02-23-2008 07:37 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome