Subaru Stalling Issues Point to Faulty Camshaft Sensor

Had almost the exact same issue with my Subaru R2 (2012). The symptoms you describe match perfectly with what I experienced, engine stalling, rough starts, and the check engine light warning. After seeing these problems, I took it to my regular workshop where they diagnosed it using their diagnostic tool. While I initially thought it was the camshaft sensor, it turned out the encoder wheel on the camshafts was defective, which was causing incorrect camshaft position readings and messing up the ignition timing. The repair involved replacing the encoder wheel and recalibrating the timing. Total cost came to 695€ including parts and labor. Since the fix, the engine has been running smoothly with no more misfires or starting issues. Before giving more specific advice, could you share: current mileage on your R1, whether you notice these issues more when the engine is cold or warm, any unusual engine sounds, Have you had the diagnostic codes read yet These details would help determine if your issue is similar to what I encountered. With some experience working on Subarus, I can say these timing-related problems are worth addressing quickly to prevent potential engine damage.

Thanks for sharing your experience. My Subaru has 64881 KM and was last serviced 3 months ago. Your encoder wheel diagnosis is interesting since the symptoms match so closely. The issues occur mainly when the engine is cold, and I hear a slight ticking noise during startup. I did get the diagnostic codes read at a local shop, they pointed to a sensor failure related to engine control systems. Based on what you shared about the repair costs and the similarities in symptoms, it seems worthwhile to have both the camshaft position sensor and encoder wheel checked. Poor ignition timing could definitely explain the stalling and rough starts I am experiencing.

Thanks for those additional details. Looking at your mileage and symptoms, it does sound even more similar to what I experienced. That ticking noise during startup combined with cold-start issues is very characteristic of encoder wheel problems in these engines. The diagnostic codes mentioning sensor failure often show up because the engine control unit receives irregular signals from the encoder wheel through the camshaft position sensor. When I had mine fixed, the mechanic explained that the encoder wheel teeth wear down over time, leading to incorrect ignition timing signals. In my case, the repair shop first tested the camshaft position sensor, which was actually working fine. The sensor was reading correctly, but the signals from the worn encoder wheel were causing the engine control system to misinterpret the camshaft position. Since your car was serviced recently, you might want to check if they noticed any timing-related issues then. The engine misfire symptoms you describe, especially during cold starts, are textbook signs of this problem. Getting it addressed soon would be smart to prevent more serious engine issues. Based on recent prices, you might be looking at around 650-700€ for a complete fix, depending on whether they need to replace both parts or just the encoder wheel.

The information you provided is really helpful, especially about checking both the encoder wheel and sensor. Since my car was recently serviced, I called the shop and they mentioned they did notice some timing irregularities but thought they were minor at the time. I have scheduled an appointment for next week to have them specifically check the encoder wheel and crankshaft sensor. The quoted price range of 650-700€ matches what they estimated for the potential repair, which makes me feel better about their assessment. The fact that your car ran perfectly after the fix gives me hope that this will resolve my engine stalling and starting problems. I will make sure they do a complete sensor testing before replacing any parts, just to be certain about what needs replacing. Will update once I get the car checked. At least now I can better explain the symptoms and potential causes to the mechanic, which should help them diagnose the issue more accurately.