Hi guys,

I just bought a 2004 Z with 90K miles from a used car dealership. Made the deal for $9k and drove off. About 5 miles into the drive the service engine light comes on and starts flashing. Misfire. Had a similar issue with an 01 Audi A4 that I had and I still have nightmares about it.

I brought it to a shop that works with this dealership to try and get it fixed for free. They are charging me $270 for an 02 sensor replacement and a coil replacement (cylinder 5). They say they are eating the labor cost for me which would have brought it up to $680.

My question is first of all if this price is legit. Second of all if it's possible they reset the ECU to hide this issue until I drove it 5 miles and the issue came back up. Did I get played???

 

If it has a miss you can't reset anything to make it go away. The CEL might go away but it will still run like ****.

For parts prices, look them up online or call a dealer parts department....

 

The oxygen sensor wouldn't make it misfire. As for part prices...look them at at your local store then add 25-30% mark-up for a shop

 

Really? Pulling the code at auto zone said it could be either O2 sensor, MAF sensor, ignition coils or spark plugs.

Wouldn't a bad O2 sensor affect the fuel/air mixture?

270 for the parts seems ok. They got all OEM so at least it is quality.

 

what was the code?

 

Po300

 

P0300 = random misfire. I'd start with the plugs and coil and work backwards.

 

I mean it's fixed. they replaced the coil for cylinder number 5 and the front O2 sensor. I will probably have to replace all the coils if one went, right? Means the others are probably close? I'll have all the plugs changed soon just for good measure.

Is there a way to test a coil's health with a multimeter or something?

 

I'd take them to a quality electrical auto engineer as he'd have kit that would be better than a multimetre, but there'd be no harm in doing a check yourself. Its usually best to replace them all at the same time just the same as with spark plugs. I'm glad you've managed to solve the problem anyway.

 

Yea, its just theyre $100 a piece and i just bought the car, was hoping to at least wait a bit to spend another $500+ on coils/plugs/90k maintenance. What am i looking for by testing with a multimeter? Proper resistance? Any idea what it should be?

 

I sent you another message on my phone last night as i had to go out and it seems that for some reason you didn't get it, or it didn't land on this site. Regardless, what i said was that i know its not what you want to hear especially as you've just bought it.
Unfortunately i don't have any figures, but something is definitely starting to break up. In the old days when cars ran coils,distributors and straight HT leads, in low light you could see purple flashes along the failing HT leads, I have no idea if this still applies what with their now being a coil on every lead. Do you have a reliable auto electrician near you who could advise you? Do you have anyone near you with a Z who'd be prepared to remove a lead and using your multi-meter test for resistance? Have you also had a look at local breakers who may have a low mileage crashed Z that you could take the leads from. Sorry I can't be of any further help as auto electrics are definitely not my strong point. Good Luck, I hope you get it sorted and for minimal cost.