A couple of months ago I got a P0420 code. I took it to the shop and being that the car only has 50K miles we deceided it was a faulty HO2 Sensor (after cat). The problem went away for a couple days then I got a P0141 (P0420 never came back so I'm thinking the cat is o.k.) I took the car back to the shop and the tech deceided the new sensor must be no good.
He replaced the sensor and a couple days later I got the P0141 code again. It seems the sensor is failing the cold start test(The heater calculated resistance is not within an expected range).
According to my manual the heater resistance test is done at startup when
DTC's p0030, p0036, and p00050 are not set (they're not)
The ignition if off for more then 8 hours(it was)
The ECT sensor is between -22f and 113f (It was)
The difference between the ECT and IAT is less then 14.4F
The last 2 times the code was thrown those were the conditions
Does anyone have any idea's on what the problem might be
my thoughts are its either a wiring problem to the PCM(connector 2 pin 56), a bad PCM, or aftermarket sensor is not sufficiant.
I may have to bring it to the dealer if I can't figure it out
I dont think the cat is bad because P0420 never came back.