Code 33, 41 and 42

DAVID1967

MEMBER
1933 FORD F-150

I have a 1992 F150 4x4 5.0L Mileage 135,000
My problem is the engine runs extremely rich so much it is coming out of the exhaust. The check engine light stays on, the 3 codes showing are 33 EGR No Pressure, 41 Always Running Lean and 42 Always Running Rich. I have Replace The MAP Sensor The EGR Position Sensor And The Oxygen Sensor.

7 Replies

TAURUSWHEEL

MECHANIC
718 POSTS

Did you receive the code 33 in koeo, or koer mode? Because depending on which one, could point to similiar but different reason, the evr may be suspect. I see you didn't replace it. For the other two codes, I would start by checking the pvc system, make sure it's operating correctly and no parts are plugged, then I would check for any possible vacuum leaks such as cracked rubber hoses and so on, check all of them including the canister purge system hoses.

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Saturday, March 17th, 2007 AT 5:50 PM

DAVID1967

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2 POSTS

I recieved the code in KOER and it was already in memory when I started working on this truck. I am also curious if all 3 are related.

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Saturday, March 17th, 2007 AT 8:27 PM

TERRYR007

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2 POSTS
1981 FORD F-150

I pulled the codes from my truck 93 F150 5.0L. These are the codes:
Code 33- EGR Vavle closed- I can deal with this one
Code 81- Air Management system 2 failure- problem here.

Can someone help me with code 81? I have no idea what air management system 2 is or where to start to troubleshoot.
Thanks,
Terry

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Tuesday, January 3rd, 2017 AT 11:44 AM (Merged)

SG1099

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1 POST
1987 FORD F-150

Engine Performance problem
1987 Ford F150 6 cyl Four Wheel Drive Manual unknow miles

i'm getting codes 33 and 42.I've replaced the oxygen sensor already and code 42 still comes up. If I get code 33 cleared up, would it correct code 42? Also what do I need to check on the EGR to clear code 33? Thank you.

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Tuesday, January 3rd, 2017 AT 11:45 AM (Merged)

JACOBANDNICKOLAS

MECHANIC
109,644 POSTS

Actually, I would think it is the other way around. Chances are the EGR is plugged with carbon and the valve isn't closing properly. As a result, you are getting a lean or rich reading for the O2 sensor.

Remove the EGR. Most times, they have carbon build up causing them to stick or not work at all. Clean the carbon from it and make sure the valve is opening and closing properly (sealing). Also, while it is off, make sure where it bolts to the intake is clean. I have seen them solid with carbon. Finally, and don't laugh, make sure hoses to the EGR are clean and free of obstruction (carbon).

Let me know what you find.