Hey guys, was wondering if you could help me out. My CEL came on last week and was going on and off, then it stayed on. OBDII scanned it and came up with

P0137: Heated Oxygen Sensor Circuit Low Voltage

and

P0300: Random/Multiple Cylinder Misfire Detected

Did a search and found a few Evos who got the P0300 code but no real explanation of why it happened or how it was resolved.

Anyone have any ideas? The car isn't doing anything to act funny or anything like that, so I'm a little stumped. Thoughts/suggestions would be appreciated.

 

You might have a dying front O2 sensor, which could be causing a poor A/F ratio, causing knock.

 

Thanks Otter. Anyway to know if thats it for sure other than replacing it?

 

You can take it to a shop (likely an exhaust/muffler shop) and have it tested.
That is unless you have a high impedence DC voltmeter and can tell when you have the engine running in closed loop.
Or an oscilloscope to test how it is reacting to oxygen changes in the exhaust.

So yeah.....Otter is right......likely need to replace it.

 

you don't need a scope to test the output voltages, the procedure is pretty simple and outlined in the tech manual.