Jeep Grand Cherokee 2000 4.7L - All Four O2 Sensors Show Same Fault (Codes 0135, 0141, 0155, 0161)
Hi everyone, I'm wondering if it's possible for all four oxygen (O2) sensors in my Jeep Grand Cherokee 2000 4.7L engine to show the same fault simultaneously. The diagnostic codes I'm seeing are: - 0135: O2 Sensor Heater Circuit Malfunction - Bank 1, Sensor 1 - 0141: O2 Sensor Heater Circuit Malfunction - Bank 1, Sensor 2 - 0155: O2 Sensor Heater Circuit Malfunction - Bank 2, Sensor 或 (Note: likely typo in original; should be Bank 2, Sensor 1) - 0161: O2 Sensor Heater Circuit Malfunction - Bank 2, Sensor 2 The vehicle starts slowly with the key but runs smoothly most of the time. Occasionally, it runs roughly for the first minute or two before settling into normal operation. On startup, I sometimes hear a loud, bus-like or heavy truck sound — the engine and fans seem to roar. Any insights or advice on this issue would be greatly appreciated. Thanks in advance!
Have you checked the O2 sensor heater circuit for upstream sensors with a 12V supply when the key is off (KOEO)? Check the downstream O2 sensor heater relay as well. Ensure all O2 sensor grounds are intact and properly connected. Any recent repairs, modifications, or engine events that might have triggered this issue? This could point to a shared wiring problem or faulty ground connection affecting all sensors simultaneously.