Codes 41+42 on 93 Explorer
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Codes 41+42 on 93 Explorer
Hi. I have a 93 Explorer 4x4 4.0 with 80,000 miles. The only EEC connector I can find is one with a cap on it labeled Anti Lock test that is identical to the EEC 4 connector. I was able to pull down 4 codes. 11,41,42,67. Obviously the ones of concern are 41 and 42. 41=EGO sensor running lean and 42=EGO sensor running rich. Quite a contadiction. Symptoms of trouble are hesitant start(usually 5 seconds to turn over), Strong gas odor from engine and from exhaust along with white smoke. I'm straying away from the head gasket being bad since I can't find anything to indicate that it might. Coolant is at level and proper color, oil is at color without any indications of mixing and Transy fluid is ok. Would a bad EGO sensor cause all of this trouble?
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From: UT
Yes it is an iteresting contradiction. It suggests to me that there might be a wiring fault rather than a faul in the O2 sensor itself. Also, I wouldn't necessarily call the 67 insignificant. The computer changes it's algorithm slightly when it thinks the transmission is in P or N. If there's a bad or intermittent fault in the PNP switch circuit, the computer might do some odd things. Here's what I'd do next.
1) You only indicate KOEO and continuous memory codes. Since, you passed the KOEO hard fault portion of the test, I'd run the KOER test. See if you are dealing with a consistent fault, or something so intermittent that it only shows up as continuous memory codes.
2) Clear the continuous memory codes (disconnect STI during anytime during KOEO or continuous memory code output), drive the truck, and see what code(s) come back.
3) Check fuel pressure. Make sure the pressure is where it should be, that it isn't leaking through the fuel pressure regulator into the intake, and that the injectors aren't stuck open.
1) You only indicate KOEO and continuous memory codes. Since, you passed the KOEO hard fault portion of the test, I'd run the KOER test. See if you are dealing with a consistent fault, or something so intermittent that it only shows up as continuous memory codes.
2) Clear the continuous memory codes (disconnect STI during anytime during KOEO or continuous memory code output), drive the truck, and see what code(s) come back.
3) Check fuel pressure. Make sure the pressure is where it should be, that it isn't leaking through the fuel pressure regulator into the intake, and that the injectors aren't stuck open.
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Forgot to mention that it seems I'm getting fuel to mix into my oil. Level was a little high so I drained excess and its currently at proper level. I had added a quart of oil 2 days before these problems started to occur. Stick said it was a quart shy but after careful thinking it was on a slight angle. Didn't think it would be enough to show as low as a qurat. Will check the regulator.
Edit: Also I don't seem to have an STI hookup. While looking for information on this problem I stumbled acoss information saying that some vehicles over 88' don't use the STI, just the STO.
Edit: Also I don't seem to have an STI hookup. While looking for information on this problem I stumbled acoss information saying that some vehicles over 88' don't use the STI, just the STO.
Last edited by cb4492; Jun 24, 2004 at 01:26 PM.
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Did the KOER test with same results. Did find one interesting thing of note. You have 3 lines running up the rail. One goes to the regulator, one to the engine somewhere(by intake) and the other one once it reaches the engine compartment switches to a rubber hose which runs about 18" or so into a plastic 90 then has about 4" of rubber tubing. This one(rubber hose) I found laying lose beneath the power steering pump. Perhaps this is the root of the matter and if so does anyone know where it goes. I've been looking non stop and can't figure it out. Also, checked regulator for fuel leaking and seems dry as a bone.
Last edited by cb4492; Jun 24, 2004 at 03:10 PM.
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All right, desperatley need help with this. I found the correct eec harness 
and heres the codes I'm getting with the KOER test.
136-HEGO sensor voltage signal not switching during test (Bank#2)
172-HEGO sensor voltage signal indicates lean(Bank#1)
412-Cannot control RPM during test
536-(I didn't perform BOO test)
538 Insufficiant RPM change during test or Invalid Cylinder balance(throttle position movement) or Invalid cylinder balance test(cylinder Identifiacation problems)
and heres the codes I'm getting with the KOER test. 136-HEGO sensor voltage signal not switching during test (Bank#2)
172-HEGO sensor voltage signal indicates lean(Bank#1)
412-Cannot control RPM during test
536-(I didn't perform BOO test)
538 Insufficiant RPM change during test or Invalid Cylinder balance(throttle position movement) or Invalid cylinder balance test(cylinder Identifiacation problems)
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From: UT
fuel getting into the oil suggests that you are really running rich rather than lean. This might lead us to believe that there is a fault in the O2 sensors or the O2 sensor circuit. However, let's not jump to conclusions too fast. False lean codes can be set during the KOER test if the engine/O2 sensors aren't given an adequate chance to warm up before the test. Was the engine cold before the KOER test? Did you run the engine for several minutes before the KOER test to make sure the O2 sensors were at operating temperature. If yes, here's what I'd do:
1) Inspect the wiring between the O2 sensors and the PCM. Make sure there are no breaks/cuts/loose connections.
2) Check fuel pressure and check for fuel in the vacuum line to the FPR.
3) Check for excessive voltage drop across the PCM's ground wires.
4) Backprobe the O2 sensor's signal circuit and monitor O2 sensor output. After an initial warm up period, the O2 sensor should put out a voltage between 0 and 1 V that varies from low to high.
1) Inspect the wiring between the O2 sensors and the PCM. Make sure there are no breaks/cuts/loose connections.
2) Check fuel pressure and check for fuel in the vacuum line to the FPR.
3) Check for excessive voltage drop across the PCM's ground wires.
4) Backprobe the O2 sensor's signal circuit and monitor O2 sensor output. After an initial warm up period, the O2 sensor should put out a voltage between 0 and 1 V that varies from low to high.
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