check engine codes.
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Freshman User
Joined: Aug 2003
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check engine codes.
ok guys, this forum helped me pull the codes on my 89 ranger. now that I got the codes I need you help in fixing my check engine light problem.
the koeo test showed the system to be normal
the koer test gave the following codes 41, 13 and 74
code 41 HEGO sensor circuit indicates system lean
code l3 low rpm during self test
code 74 brake on/off circuit failure (did not have parking brake on--I thnk.
I would think code 41 is the cause of my check engine light. what is it , where is it, and how do I go about fixing it.
In New Jersey, the vehicle will fail inspection if the check engine light is on so I need to get this light to go out.
the truck is a 89 with a 87 transplanted 2.9l motor. could the different year motor be causing the check engine light. The old egr plumbing is still on the motor and I have not blocked off the tube from the header to the egr valve.
Tom
the koeo test showed the system to be normal
the koer test gave the following codes 41, 13 and 74
code 41 HEGO sensor circuit indicates system lean
code l3 low rpm during self test
code 74 brake on/off circuit failure (did not have parking brake on--I thnk.
I would think code 41 is the cause of my check engine light. what is it , where is it, and how do I go about fixing it.
In New Jersey, the vehicle will fail inspection if the check engine light is on so I need to get this light to go out.
the truck is a 89 with a 87 transplanted 2.9l motor. could the different year motor be causing the check engine light. The old egr plumbing is still on the motor and I have not blocked off the tube from the header to the egr valve.
Tom
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Joined: Dec 2001
Posts: 3,742
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From: UT
KOER 74 is almost always operator error during the test. Did you press on the brake shortly after engine id was output?
KOER 13 is usually just symptomatic.
An easy cause of a KOER 41 is to perform the test on a cold engine. The O2 sensor isn't functional until the sensor reaches its operating temperature (600 F or so). The short duration fo the test isn't long enough to get the sensor up to temperature.
If you're certain the sensor was preheated prior to the test, then you need to determine the cause of the lean signal. Is the engine actually running lean as indicated by the sensor, or is it running rich? Wiring between the computer and the sensor intact? Any vacuum leaks? fuel pressure correct?
KOER 13 is usually just symptomatic.
An easy cause of a KOER 41 is to perform the test on a cold engine. The O2 sensor isn't functional until the sensor reaches its operating temperature (600 F or so). The short duration fo the test isn't long enough to get the sensor up to temperature.
If you're certain the sensor was preheated prior to the test, then you need to determine the cause of the lean signal. Is the engine actually running lean as indicated by the sensor, or is it running rich? Wiring between the computer and the sensor intact? Any vacuum leaks? fuel pressure correct?
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motor was up to operating temperature. did test after driving the truck about 20 minutes.
the strange think about this check engine light is that it takes about 10 minutes after starting the truck that the light comes on. If I shut off the motor and restart the truck the light will not appear for another 10 minutes.
The check engine light has been apearing since I swapped a 87 motor into the 89 ranger. The 87 had the egr plumbing--would the tube from the header to the egr valve be causing the code--should the tube from the hearder to the egr valve be pinched off?
Also, since the 87 motor was swapped with the headers, is the o2 sensor on the 87 motor different that the 89 2.9 motor??
the strange think about this check engine light is that it takes about 10 minutes after starting the truck that the light comes on. If I shut off the motor and restart the truck the light will not appear for another 10 minutes.
The check engine light has been apearing since I swapped a 87 motor into the 89 ranger. The 87 had the egr plumbing--would the tube from the header to the egr valve be causing the code--should the tube from the hearder to the egr valve be pinched off?
Also, since the 87 motor was swapped with the headers, is the o2 sensor on the 87 motor different that the 89 2.9 motor??
Posting Guru
Joined: May 2002
Posts: 1,574
Likes: 1
From: Phoenix
If you still have the EGR valve connected but no vac lines hooked up, then it should not leak. If the EGR valve leaks internally, you could be injecting exhaust into your manifold but the non-EGR computer is not compenasting and would actually cause a rich exhaust mixture. Rich because there is not enough available oxygen to burn all the fuel. Since you are getting a lean code, I'd say the EGR is really affecting this.
Did you look at the O2 sensors? I had one that leaked exhaust out to the environment, contaminiated the sensor's reference air and gave back a lean code. PCM compensated byt adding more fuel. Plugs got sooty black - rich not lean. Sensor was also sooty black from it's internal leak to the outside. Changed sensor, reset computer and all was happy again.
Did you look at the O2 sensors? I had one that leaked exhaust out to the environment, contaminiated the sensor's reference air and gave back a lean code. PCM compensated byt adding more fuel. Plugs got sooty black - rich not lean. Sensor was also sooty black from it's internal leak to the outside. Changed sensor, reset computer and all was happy again.
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