I have a 2001 Limited. 3.5l engine. I have been getting this trouble code off and on over the last several months. It only happens when I'm fully loaded (roof rack full of wind resistant items) and traveling up hill or into a headwind at highway speeds. I recently started pulling a 2000 lb trailer and I get the same thing only when it seems like I'm really straining the engine, that is going up hills or into strong headwinds while trying to maintain 70mph.

Then the light comes on. Read the code, and get DTC 125.

If I clear the code and then drive around town for several months, I never see the code again until I repeat the scenario described above.

The service manual indicates the following:

p. 13A-71: "Excessive time to enter closed loop fuel control circuit"
p. 13A-72 indicates that the following are the most likely causes:
* Heated oxygen sensor failed
* Injector failed
* Fuel pressure regulator failed
* Fuel pump failed
* Fuel filter is clogged
* Intake system vacuum leak
* Exhaust leak
* PCM failed

My dealer is telling me that it's my full-size skid plate that I have covering my trasmission, because it covers the full width of the vehicle and covers the muffler. They claim that the extra heat caused by this (the muffler does get extremely hot, but I thought this might be caused by something else more internal) is causing exhaust problems which is potentially throwing this code.

So, now to the questions:

1) Does anyone here have any experience with this code on their Montero?

2) Does anyone have any reason to believe that a skid plate that's at least a few inches below the muffler could trap enough heat to not only cause the muffler to overheat, but also throw this Diagnostic Trouble Code?

Many thanks for your assistance.

Tony

There are some TSBs (TSB-03-13-001, TSB-04-13-011, TSB-05-13-009, TSB-07-13-002) for this code. It involves a PCM reflash, and on '01 models it may also involve replacing all four of the oxygen sensors. If this hasn't been performed on your truck already, the dealership should have told you about it. If it has been performed, the first thing I'd check would be the oxygen sensors, assuming you don't have any exhaust or vacuum leaks. I've never fixed one with this DTC before, but I looked on Mitchell and on iATN and this is my best guess.

Take a look here..

ODB CODES web page..

Thanks, gentlemen, for the info. I'll look into it.

Anyone else have skid plates over the muffler? Does it cause excessive heat from the muffler?