2009 Jeep Rubicon 3.8L Manual 2DR P0335 Crank Sensor Issue: How Does It Start Without the Sensor?
Hi everyone, I'm having a question about my 2009 Jeep Rubicon 3.8L manual 2-door model. I recently received a P0335 diagnostic code, which indicates a crank position sensor (CKP) fault. I removed the crank sensor to install a new one and was surprised to find that the vehicle started up without it — no error code appeared when I turned the key on. The engine did start, but it ran with noticeable misfires and poor performance. How is this possible if the crank position sensor is completely removed? I've confirmed the issue is not related to fuel or ignition systems, and I'm wondering whether the ECU can operate in a limited mode without the CKP sensor. Any insights into how the PCM (Powertrain Control Module) might simulate crankshaft position data using other sensors like the camshaft position sensor? Thanks for your help! David
You should verify the circuit wiring before replacing the sensor — P0335 often points to a wiring issue, not just a faulty sensor. Always check for loose connections or damaged harnesses. Make sure you're using an OEM Jeep crank position sensor; aftermarket sensors can cause intermittent faults and may not provide reliable signals. The PCM in modern vehicles like the 2009 Jeep Rubicon has built-in fault tolerance — it can simulate CKP data using camshaft position (CMP) sensor input, allowing limited engine operation under limp mode. This explains why your vehicle started despite missing the crank sensor. Important: Always scan for codes with a proper OBD2 scanner instead of simply turning the key on and off. A simple power-on test might miss hidden faults. Once you've replaced the sensor, please update here — how does it perform now? PS: Never try to 'challenge' or bypass the PCM — they are expensive and can cause further damage. Always consult forums like this one before attempting such actions.