intermittent check engine light
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intermittent check engine light
Hi . New to the site, but I have learned much reading the posts!
I have a 94 Explorere w/93,000 miles on it. It runs fine in town and I get great mileage.
The problem is that after driving over 50mph for an hour or more, the CEL comes on for a bit, then off. One time it stalled. We let it rest for a while and it started again, no problems. The light never stays on.
I pulled the codes yesterday and here is what I got:
KOEO:
335 -- EGR (PFE sensor or EPT) signal higher or lower than expected
176 -- 02 sensor lean (bank 2)
177 -- O2 sensor rich (bank 2)
KOER
326 -- EGR (PFE sensor or EPT) voltage lower than expected.
My questions are: Which is bank 2 for the O2 sensor?
What/where are the PFE/EPT sensor.
Should I replace both of these sensors or could one make a false reading of the other?
Thanks!
I have a 94 Explorere w/93,000 miles on it. It runs fine in town and I get great mileage.
The problem is that after driving over 50mph for an hour or more, the CEL comes on for a bit, then off. One time it stalled. We let it rest for a while and it started again, no problems. The light never stays on.
I pulled the codes yesterday and here is what I got:
KOEO:
335 -- EGR (PFE sensor or EPT) signal higher or lower than expected
176 -- 02 sensor lean (bank 2)
177 -- O2 sensor rich (bank 2)
KOER
326 -- EGR (PFE sensor or EPT) voltage lower than expected.
My questions are: Which is bank 2 for the O2 sensor?
What/where are the PFE/EPT sensor.
Should I replace both of these sensors or could one make a false reading of the other?
Thanks!
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Joined: Nov 2002
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From: Iowa City,IA
Fishes,
I was having similar problems with my 94 with about the same mileage. I tried the EGR system, the fuel pressure regulator and ECT. Still had problems so I went to Ford and they replaced O2 sensors. So far no more cel's. I think you can still read the full post under " Engine can't make up its mind to be lean or rich" Hope it helps.
I was having similar problems with my 94 with about the same mileage. I tried the EGR system, the fuel pressure regulator and ECT. Still had problems so I went to Ford and they replaced O2 sensors. So far no more cel's. I think you can still read the full post under " Engine can't make up its mind to be lean or rich" Hope it helps.
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Joined: Dec 2001
Posts: 3,742
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From: UT
Are any of those KOEO codes hard faults (1st section of codes before separator pulse) or are they all continuous memory codes (after separator pulse)? If you diagnose/repair "by the book" you are supposed to resolve all KOEO hard faults (sometimes referred to simply as KOEO codes), then turn your attention to KOER codes. Only after resolving both of those sets of codes do you turn your attention to continuous memory codes.
The reason I ask that is because, if the 335 is a hard fault (as I suspect it is), then it almost has to be an electrical fault (either in the PFE sensor or wiring), because the engine isn't running.
The reason I ask that is because, if the 335 is a hard fault (as I suspect it is), then it almost has to be an electrical fault (either in the PFE sensor or wiring), because the engine isn't running.
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Thanks for the replies!
Yes, The 335 was the hard fault and the ones relating to the O2 sensors were in continuous memory.
So far, I've just replaced the PFE sensor, and cleared the codes Took it out on the HWY and drove it for about an hour, no cel.
I hope this is the fix. It's so hard to tell because the light didn't/doesn't come on until we had been driving on the freeway for some time and never stayed on.
Bamohr -- I did read your post and found similar problems Thats why I wanted to know about one sensor making false readings from the other. Thanks. (It's probably about time to change the O2s anyway)
Mrshorty -- thanks for the info on the "proper" order. I had read that on another post (from you I think) and that's why I went with the PFE sensor first.
Hopfully, this was the problem. Thanks again
Should I go ahead with changing the o2 senor(s)?
Yes, The 335 was the hard fault and the ones relating to the O2 sensors were in continuous memory.
So far, I've just replaced the PFE sensor, and cleared the codes Took it out on the HWY and drove it for about an hour, no cel.
I hope this is the fix. It's so hard to tell because the light didn't/doesn't come on until we had been driving on the freeway for some time and never stayed on.
Bamohr -- I did read your post and found similar problems Thats why I wanted to know about one sensor making false readings from the other. Thanks. (It's probably about time to change the O2s anyway)
Mrshorty -- thanks for the info on the "proper" order. I had read that on another post (from you I think) and that's why I went with the PFE sensor first.
Hopfully, this was the problem. Thanks again
Should I go ahead with changing the o2 senor(s)?
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Joined: Dec 2003
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Had a similar problem and fixed by changing the fuel filter, air filter, pcv valve, and new wires. Basically the thing wasn't running up to the sensors liking even though it ran great, sounded great and the mileage was good. I had 80K. Sure was cheaper and easier than the sensors. I started that route and when I got to the multi hundred PFE (or whatever it was) I decided the basic maintenance was a better first step. Remember, the codes don't necessarily mean the sensor is bad, it means the data from that sensor is out of expected range fo rthe computer's liking!!!!
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