I am getting these codes on my 01 Mitsubishi Montero Limited. P0155, p0170, p0125, and p0155. Any help is appreciated.


Asked by Feb 13, 2015 at 11:46 AM about the 2001 Mitsubishi Montero Sport 3.5 XS 4WD

Question type: Maintenance & Repair

Been driving great until today. It started
dying when I take my foot off the gas. It to
me was acting like it wasn't getting gas.

5 Answers


P0155: O2 Sensor Heater Circuit Malfunction (Bank 2 Sensor 1). P0170 Fuel Trim Malfunction (Bank 1). P0125 Mitsubishi - Insufficient Coolant Temperature for Closed Loop Fuel Control. You have P0155 on here twice. Sound like you a have a few things going on. O2 sensor isn't a big deal but the other two could be I would have Your Montero looked at soon by a REPUTABLE mechanic.

2 of 2 people found this helpful.

When you first start your car, it's in 'open loop', the signals from the O2 sensors are ignored, to get a slightly rich mix for cold start. Then the engine, O2 sensors heat up, and in your case it is not warmed up enough to go in to closed loop, and that plays right in with the o2 sensor not being heated. (P0155) and the sensor its self may not be bad, but the heat circuit to it. Bottom line, just do what TransAm77 suggests, you really do need a mechanic

2 of 2 people found this helpful.
Best Answer Mark helpful

Thanks for a more detailed explanation FordNut.

1 of 1 people found this helpful.

Thanks for the help. I now have everything fixed except for a fuel trim code. Any ideas on that will be appreciated. Thanks for the help.

1 of 1 people found this helpful.

That should fix the fuel trim, Brandy, fuel trim is the ratio of air to gas, 14.7:1 optimal for most cars at operating temperature.. if everything got fixed, so is that. Just might have to clear the codes, and the light will not re-appear

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