I havent posted in quite a while, but I have a 2002 Infiniti I35 with 129k miles. I have been really disappointed in the quality of this car. I have been driving around for 5 months with an expired inspection because of a bad o2 sensor, according to my scanguage, staring at a CEL. I put some new Kumhos on it, and I'm just about ready to spring for the o2 sensor.
Well, i slapped in a new air filter, drove it to work & home (about 80 miles), hopped in it the next morning, and no CEL. Drove the **** out of it for the 130 mile commute, and got it inspected on the way home. No codes whatsoever!
The previous air filter was not that dirty! Someone please explain to me what the hell is going on! Maybe the lesson learned is change your air filter before shelling out a ton of money for some assinine sensor...

 

What was the code you got?
If it was for o2 failure it could still come back...

 

Ive got 'em written down somewhere...

P0159
P1167
P0021

 

A clogged air filter can set and o2 sensor code. If the engine is getting to little air you will get a o2 sensor bank 1 or 2 rich code since there is more fuel being unburned due to lack of air.

Post the code when you get time.

 

Hmm well

P1167 is - Heated Rear Oxygen Sensor 2 Maximum Voltage Monitoring Bank 2

P0159 is - O2 Sensor Circuit Slow Response Bank 2 Sensor 2

Possible causes for those 2 our.

- Faulty Rear Heated Oxygen Sensor Bank 2
- Clogged air filter
- Rear Heated Oxygen Sensor Bank 2 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 2 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks

And P0021 is - Intake Valve Timing Control Performance Bank 2

- Faulty Camshaft Position Sensor
- Camshaft Position Sensor harness is open or shorted
- Camshaft Position Sensor circuit poor electrical connection
- Faulty Intake Valve Timing Control Solenoid Valve
- Intake Valve Timing Control Solenoid Valve harness is open or shorted
- Intake Valve Timing Control Solenoid Valve circuit poor electrical connection
- Faulty Crankshaft Position Sensor (POS)


Now the first 2 can be caused by a clogged air filter but still maybe be on there way out but both codes point to rear back sensor 2.

The other one is normally caused by a bad camshaft sensor.