Caliber Power Loss: ECU Issues vs Common Culprits

I had almost the exact same engine performance issues with my 2008 Avenger. Having some experience with basic car diagnostics, I initially thought it was the ECU too, but it turned out to be the main relay causing the problems. The symptoms were identical, power loss, check engine light, and vehicle electronics acting up. After multiple attempts at diagnosing the issue myself using a basic scanner, I took it to a workshop specializing in engine control systems. Their professional car diagnostics revealed the main relay was failing intermittently, causing ECU communication problems. The fix was straightforward, replacing the main relay resolved all issues. Total cost was 120€ including parts and labor. Much cheaper than replacing the entire ECU. Could you share: What error codes your scanner is showing? Does the issue happen more when the engine is hot or cold? Are there any other electrical symptoms, like dim lights or slow starter? This information would help determine if your Caliber has the same root cause. The ECU repair might not be necessary if its just the relay causing communication problems.

Last service was at 63000KM, still having issues despite the recent maintenance. To provide more context about the error codes, P0340 and P0335 keep showing up consistently. These symptoms started occurring right after a particularly hot day last week. Since replacing the battery and cleaning the connections saw no improvement, I am leaning towards the computer module being the culprit. The control system issues persist whether the engine is hot or cold, and there are no other electrical problems to report, starter and lights work perfectly fine. Based on your experience with the relay, I will have that checked before committing to a full ECU replacement. The automotive electronics diagnosis at my usual shop was inconclusive, so finding a specialist might be the way to go.

Thanks for the additional details about your Caliber. The error codes you mentioned (P0340 and P0335) are actually quite different from what I experienced with my Avenger. These codes typically point to crankshaft and camshaft position sensor issues rather than a faulty ECU or relay. In my case, the main relay problems caused unusual misfires and general electrical gremlins. Your consistent sensor-related codes suggest a different root cause. The fact that engine performance issues started after a hot day makes sensor failure even more likely, as these components can be sensitive to extreme temperatures. Before touching the ECU, I would strongly recommend: 1. Testing both position sensors 2. Checking the wiring harness for any heat damage 3. Verifying sensor connector integrity When my engine control system was acting up, I learned the hard way that jumping straight to ECU repair can be an expensive mistake. A professional shop with experience in automotive electronics should be able to test these sensors for around 80€-150€. The good news is that if it is just sensors, the fix would cost significantly less than a new ECU. Would you like me to share the specific testing procedure my mechanic used for diagnosing sensor issues?

Your engine control system symptoms definitely warrant further investigation before replacing the ECU. The codes you mentioned pointing to sensor issues make a lot of sense, and I appreciate the detailed relay experience you shared. My situation does seem distinct since these codes specifically relate to position sensors. After reading your response, I checked with another workshop that specializes in car diagnostics and computer module repairs. They quoted 120€ just for comprehensive testing of the crankshaft and camshaft sensors. If those turn out to be the problem, total repair costs including parts would be around 400€, still better than a full ECU replacement. I will proceed with the sensor testing first, following your suggested diagnostic steps. The engine performance issues staying consistent regardless of temperature does make sensor failure seem likely. Really helpful to know about checking the wiring harness for heat damage too, I hadnt considered that. Yes, I would be very interested in learning more about the specific testing procedure your mechanic used. Planning to bring this information to my next workshop visit to ensure they cover all bases.