jglaw

Recently my car (02 Infiniti I35) was running very poorly at idle. I turns out I had a bad ignition coil on cylinder 3 and it was replaced at my shop. They also did a fuel system clean with BG 44K. Everything seemed fine (this was on Wednesday) and it was running better than ever.

Yesterday, I took the car out and the SES light came on! Took it to Advanced Auto to get the codes read and I was pretty upset. Two P00021 codes for the Camshaft Position sensor - Timing over advance - Bank 2. A P0300 code for random multiple misfires, and two other codes (forgot the numbers) for Cylinder 4 and 6 misfires.

The strange thing is the car feels fine! I could definitely tell when the ignition coil on cylinder 3 went bad, it was idling horribly, but I can't tell anything now!

I have a feeling it may just be the camshaft sensor, and have found out that these can go bad on the I35 by searching the site. There was a time over the summer when I was low on oil and got the P00021 codes, maybe I burnt the sensor out by running low on oil? Maybe it's just bad?

Any help will be appreciated! Hopefully this is just a $50 sensor, I can't afford to replace another ignition coil right now unless it's on the front side of the engine!

shiftdrift06

Having a bad camshaft sensor would also cause random misfire. The ecu uses the cam sensors to change timing and firing sequence.

Try unplugging them and see if anything happens.

jglaw

And if every coil makes the engine run worse, then replace the sensor I'm guessing?

jglaw

You mean unplugging the sensors, not the coils don't you...?

jglaw

Unplugged the bank 2 camshaft pos. sensor today and the motor died. Is this just a fail-safe?
I'm debating whether to take this to the dealer or just replace the sensor and see if that helps. Is it possible the sensor is still functioning partially? Is it more likely that the car truly has a timing issue?

jglaw

Update:

Replaced the cam position sensor and the SES light went off about a day later