Question

2009 Jeep Commander 3.7L with engine code P0034, P0038 and P0304. I got 3 codes, is it likely that one code is the cause for all 3?

Answer 1

The P0034 is not a good number, the factory service manual does not show that code.

The P0304 is for cylinder misfire, common causes are the spark plugs, ignition coil or fuel injector. A cylinder misfire could cause the P0038, which is for the Oxygen Sensor.

P0304 Jeep Code - Cylinder Misfire Fault Detected
Read more: https://www.autocodes.com/p0304_jeep.html

P0038 Jeep Code - O2 Sensor 1/2 Heater Circuit High
Read more: https://www.autocodes.com/p0038_jeep.html