Codes 41 & 91 O2 related. What do I look for?

[larrym1961]

My wideband is showing a lean @ idle condition that I had mentioned in a
recent thread.

I purchased a new digital code reader (I had the old blinking light type) that jrichker (the code guru) had mentioned about on one of his replies, from Midway Auto. So I thought I would give it a test today and I got a code 15 (SCT chip related) and in the continuous memory I have the 41 and 91 codes. What do I look for to fix these O2 related codes?

I had an earlier problem of oil being pulled through the PVC line into the intake. that I have fixed. Is it possible when all this oil was comming through the intake it may have coated my O2 sensors and ruined them?
Before the oiling, they were brand new Motorcraft sensors.

 

[HISSIN50]

Any vacuum leaks?

 

[Mustang5L5]

Vac leaks are where I'd start looking. See if you can find any.

If not, I'd prob replace an o2 sensor and see if that causes one of the codes to go away.

Rock auto has motor craft o2 sensors for under $40

 

[larrym1961]

I had a Major vaccume leak due to failed Fel Pro 1250 intake gaskets. The gaskets have been replaced, and the vaccume leak fixed. I ran a code check prior to the gasket replacement. and got code 11 without the SCT chip. The 41 and 91 codes have appeared just recently. After the fix. and the mentioned intake oiling feasco. My mustang literly looked like I had a multi million mile motor it was smoking that bad!

 

[Mustang5L5]

Usually, when 41 and 91 appear together, the cause is something other than the sensor.

It is possible both have failed. Can you visually inspect to see if they are oil soaked?

 

[HISSIN50]

Might also make sure your MAF is functioning properly and isn't dirty.

 

[larrym1961]

Well I checked O2 sensors, look normal to me, so I dissconected battery, reconected 1/2 hour later then took for a drive. Then I re-tested and got a code 11 this time. I will drive a few more days and re-test again.

Thanks guys for those items to check!

 

[Mustang5L5]

Def recheck after maybe a week or so and make sure they stay gone.