[Chuck123]

2003 Baja 2.5 --
So, I started out with the occasional misfires on 3 & 4, the 0032 and the 0030 and a rattle.

I got a new (Walker) CAT and two cheap sensors off amazon. (The back cat was toast)

I started getting 0032 & 0037. Cleared a few times and came back immediately.

- figured it had to be the cheap sensors so I ordered a new A/F sensor (pricier Densi)

- while I wait for that to arrive, I thought, "Hey - I'll replace the O2 sensor after the CAT with the old one from the old cat and see what happens.

- I switch 'em and drive on over to the parts store to clear the codes and check it out.

- unsurprisingly, when I got there, I had the 0032 & 0037 to clear - PLUS the return of the 0030 (pending).

- I cleared 'em - expecting to take a 10 minute drive and have them all return.

I've taken 6 or 8 ten minute drives today now and ZERO codes! ?? wth?!

- next morning - still no codes - intermittently at idle it's fluctuating between 750 & 1250 rpms... (?) drove 5 minutes and that stopped, but, cause?

Doe any of that make ANY sense to ANYbody??

 

[idosubaru]

Intermittent codes are the norm, not the exception.

0030 and 0032 are sensor specific codes. replace that sensor. it should be OEM brand. if that doesn't fix it, investigate the associated sensor connector and wiring. pay particular attention to rodent damage or prior work in that area (engine, trans removal, etc). test continuity from sensor connector to ECU or connector on top of transmission or just get a free FSM online and follow that trouble shooting for that code.

cylinder misfires are usually plugs/wires or oil in the spark plug tubes.

 

[Chuck123]

Yeah - but it was sooo consistent - then nothing??
I know they could come back but still weird considering, isn't it?

Intermittent codes are the norm, not the exception.

0030 and 0032 are sensor specific codes. replace that sensor. it should be OEM brand. if that doesn't fix it, investigate the associated sensor connector and wiring. pay particular attention to rodent damage or prior work in that area (engine, trans removal, etc). test continuity from sensor connector to ECU or connector on top of transmission or just get a free FSM online and follow that trouble shooting for that code.

cylinder misfires are usually plugs/wires or oil in the spark plug tubes.

 

[idosubaru]

Yeah - but it was sooo consistent - then nothing??

were you clearing it daily for months and it came back on immediately, the same time, every day?

I know they could come back but still weird considering, isn't it?

Yes and no. “Yes” for the feeling of not understanding why/how sensors work and exhaust ones particularly are sometimes odd, but “no” because it is common.

 

[eagleeye]

my h4 has denso o2 sensors on it. 114,000 miles at present.

rear one replaced 2x for p0420,

front A/F one replaced 1x for p0130.

rodent damage on the wires leading up into the car from the sensor seems likely.