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Help w/ Codes


Active Member
January 14, 2007
Reaction score
City, State
Martinsburg, WV
Year, Model & Trim Level
'92 XLT / '93 XLT
Check Engine light keeps coming on...need Help w/ Codes

The light comes on about 30 mins into my drive. It will go away if I turn the truck off and then back on, but the codes are still there...

I need help figuring the following codes out:

172, 181, 185, 186, 187

They are pointing to a bad Fuel Temperature Sensor, but I can't find any documentation on it, and the parts store has never heard of it.

Any help would be much appreciated!!!

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172 koer, continuous memory (c) heated o2 sensor indicates lean condition, right side
181 (c) adaptive fuel rich limit reached at part throttle, right side
185 (c) Mass air flow lower than expected
186 (c) Injector pulse width higher than expected
187 (c) Injector pulse width lower than expected

these are right out of a haynes repair manual.

i would agree with Brooklynbay, it is a lean condition. may be a faulty o2 sensor... although u should do a vacum leak test first... check hard rubber lines as the tend to become brittle and break...
172 is a hard code, the rest are in the memory... clear your memory and drive it for a day to see if any of the other codes return... happy solving:D

I have checked and found no vacuum leaks. All the connections are tight and brittle hoses and connections had already been replaced. I had some in the past, which might account for the ones in memory. I can only assume that this means that there is a bad O2 sensor. I will be trying that next.

If anyone can think of anything else, that would be great!!!

Maybe the intake manifold gasket is leaking?

Lean codes might be the most difficult to diagnose. Without further diagnosis, it can't be determined if the O2 sensor is at fault or not.

"By the book" one of the first tests when you have an O2 sensor code is to check the fuel pressure. Low fuel pressure can trigger a lean code.

Are there other symptoms that indicate whether the engine is acutally running lean as reported by the sensor or if the engine is really running rich (false lean signal from the sensor)?

Some people (even some professionals) feel that the O2 sensor needs to be replaced periodically anyway. You only have one, and some would suggest just replacing the sensor if it's been in there a while as an "educated guess". If it fixes the problem, then you can move on. If it doesn't, then you can go about diagnosing the problem further.

If you decide to go this route, just realize that you don't want to get too caught up in the "guess and check" method. Things can get expensive pretty quick.