Need some serious help. I have to get this fixed. This car is going to my girlfriends kid when he passes his drivers test and it has to pass inspection. Turning off the code just before inspection is not the answer.
2003 forester x- I have had P0420 code since June(ish) 2019. No other codes except the occasional fan rationality check code which I'm pretty sure I resolved with the new Coolant temp sensor.
An engine with 120K(ish) was put in the car in December of 2018 after the original blew up from catastrophic head gasket failure. It has about 155K(ish) on it now. My odometer says 310K it read 275K when the engine was replaced.
Since first getting P0420 I have done the following:
New PCV valve, new NGK spark plugs, new NGK wires, New fuel filter in the tank and under the hood, new IAT, new coolant temp sensor, new denso A/F sensor and 02 sensor, new eastern CAT. No exhaust leaks and from what I can tell no vacuum leaks. Most of the vacuum line were replaced anyway.
I have done the seafoam intake cleaner. I did the high concentrate on a low tank of gas injector cleaner twice.
My generic scanner says Cat monitor incomplete.
Fuel economy seems ok. It's not excessively bad. Performance is decent. Don't know about emissions since my state doesn't do vehicle inspections. My profile says I'm in NC but actually live in SC.
The Scan tool shows the A/F sensor at 2v +- and the 02 Sensor bouncing but hovering at .5v. I have read that the A/F sensor is supposed to read .1-.9 and fluctuate and the mixture is adjusted by the ECM. However, the scantool shows you a voltage that is read from the ECM concerning the A/F sensor and converted so I the 2.1- 1.9 ish readings are good.
Freeze frame from the last code set after resetting.
RPM 2288
Load calc % 12.99
MAP Hg 12.4
Coolant temp 192
ST Ftrm -0.06
LT Ftrm 7.8
MPH 57
Closed loop
