mazda 3 p0032 and p0038 codes

Hey all,

I was wondering if anyone on this forum could help me.

About 6 months ago I had headers installed on my car and of course, along came the CEL.

The codes I am getting are:
P0032 HO2S Heater Control Circuit High (Bank 1 Sensor 1)
P0038 HO2S Heater Control Circuit High (Bank 1 Sensor 2)

I have replaced both o2 sensors THREE times and they code still comes up, so I have concluded that it cant be a stuffed sensor. The sensors I replaced them with are genuine Mazda parts.

I have been told that it might not be the o2 sensor, and it might be the wiring instead. Every time I have installed a new o2 sensor I have checked all the wiring and as far as I am concerned everything from the sensor to the connector plug seems fine.

For 6 months I have been stuffing around trying to work out what is wrong with it and I have come to no conclusion.

Does anyone know what else it could possibly mean?
Has anyone had these error codes before?


thanks for the help.

Sorry, I forgot to add:
In case it matters, Ill list my mods.
CAI, Headers with 2.25inch exhaust and the advanced timing mod.
my car is the 2L model.

also, I was just thinking, is it possible that they could be coming up because my exhaust might not be grounded properly?

what brand of 02's? the light came on right after the header install? any exhaust leaks near the 02's? did you check the wiring with a dvom? do you have a wiring manual for the car?

The o2's I got are genuine mazda parts, which are NTK sensors. Im not sure what a dvom is, but I did check them with a multimetre. I got the exhaust checked at an exhaust shop, and there is no leaks. I dont have a wiring manual for the car, but every time I put a new sensor in, I check the wiring from the o2 sensor to the connector plug and it seems fine.

The CEL didnt come on as soon as I put the headers on. This is what happened:

When I got it installed and started to drive home, everything was fine. About 20mins into my drive, the CEL came on. I did a bit of investigating and noticed that the idiots who installed my exhaust didnt clip the wiring looms for the o2 sensors back in place, so the wires melted and shorted against the headers.

I replaced the o2 sensors, including new looms, the next week and the light was still on.
Every time I cleared the code, it would come back on.
I replaced the sensors again, and still the light is on.

Is there a fuse that could have blown?

does anybody have any idea what going on?

Thanks again for the help!!!

The wires must be dammaged... That explains the problem. Because you are explaining us the wires were melted that gives the clue.
Eventhough you checked the wires and voltage doesn´t meen you are 100% sure they aren´t failing.
What you have to do now is recheck wire by wire, not only the voltage and signal wires (could be a ground wire being dammaged and you didn´t noticed) all wires.
Check continuity and resistance you must have an opened or dammaged wire.

the wires that initially got damaged have been replaced........3 times!

That is what im trying to say.

When the wires got damages, I replaced the o2 sensors and the wires. When the codes still appeared, I replaced them again......and again.

so obviously a fuse, fusible link etc that powers up the o2 heaters is damaged, or the pcm drivers from the short circuits from the idiots exhaust install. dvom is digital voltage ohm meter,
you're going to need one and a wiring manual to fix this or take it to the dealer and hope that the pcm isn't shot, because melting wires from a header install that goes wrong and shorts the pcm out isn't considered warrantiable!

Ill see if I can find a wiring diagram. Hopefully it is a fuse, because im not forking out the cash for a new PCM!!!

anyone got any other ideas?

thanks for the help.

ok,
also you should try to check the ground wires (O2 ground).
Could be that when those guys installed the header they disconnected a ground wire (some times there is a little and not noticeable wire bolted with a tiny bolt in some part of the metal engine, body etc.).
For example if one ground wire is disconnected or dammaged you will not noticed it, but the sensor consecuentelly will lose the signal because it wants to ground the signal in some metal part of the car.

When I reffered to the O2 ground wire I´m not reffering necesarelly the ground wire has to be the wire from the O2. There are more ground wires bolted on the engine block or engine room, those ones supplies ground signals to many sensors (in these case could be the one for the 02 sensor).

Check all the ground wires available into the engine room and be sure they are not disconnected or dammaged ..¡

Keep posted

UPDATE:

Today I decided to check the fuses for my o2 sensors. Now I feel massively stupid for never doing this in the first place!!!

Both are missing!

My guess is the the exhaust shop got rid of them thinking that it would make my o2 light go away. I have no idea why anyone else would do this. fuckers.

thakns for all the help.

Thanks for the update, so many people never come back and post the results. I'm glad you got it resolved and it wasn't so bad in the end

That's too funny! they probably meltted before the shop gave the car back to you and they were too stupid to order new ones

can someone please tell me where the 02 sensor fuse is located