I did a quick search and found that p0300 is Random/Multiple Cylinder Misfire Detected and p1284 is Air Fuel Ratio (A/F) Sensor 1 Rich Shift Monitoring Bank 2. Am I correct to assume that the pre-cat O2 sensor on the driver side of the motor needs to be replaced? How hard is it to get to it? A few days before the codes came on I developed an exhaust leak. Can that have anything to do with the codes?

 

Sensor #1 is closest to the motor. They are numbered from the motor back.
Bank #2 is the same side as cylinder #2.
We have several how to remove catalytic converter threads. Very informative.

 

I already posted in the other forum, but it's being stupid slow right now so I don't know if it went through or not. I'll just post here, too.



My Z throws the P0300 code every once in a while but I just clear them and everything's fine.

Bank 2 Sensor 1 means driver's side pre-cat O2 sensor, yes. If the exhaust leak is on the driver's side before the cat, then the Sensor 2 is probably thinking that your car's running lean (due to the exhaust leak introducing unmetered air) which is then causing the engine to run richer to compensate. Fix the leak and you'll probably fix the O2 sensor code, although you could have fouled the Sensor 2 with the extra fuel being dumped. If that's the case, you'll have to replace and it'll be a ***** to get to it but not impossible.

 

Never mind. I thought this was important. Important enough to say “thanks” or simply reply.