2009 Chevy Cobalt Tachometer Failure, Engine Misfires and Stalls - P0336 Code Diagnosis
2009 Chevrolet Cobalt 2.2L engine: The ignition switch was recalled and replaced approximately two years ago. I currently have six keys for this vehicle, and while the dealer successfully programmed four of them, all keys have functioned normally until recently. I am now experiencing intermittent tachometer failure, engine misfires, and sudden stalling. Occasionally, the check engine light illuminates. After a brief shutdown period, the engine typically restarts and runs smoothly without any warning lights. The first time this occurred, the theft protection light activated, but the vehicle started successfully using a different key. Following the fourth incident, a local mechanic diagnosed code P033-6. I have since purchased both a crankshaft position sensor and a camshaft position sensor. I've inspected all wiring connections to the ECM and sensors, and they appear intact. While it's possible that the issue stems from faulty wiring or an ECM malfunction, I'm seeking clarity on whether replacing the crankshaft position sensor can be done without a scan tool, and if there is a 'learn' process required for either sensor. Could this issue be related to the vehicle’s theft protection system? Any guidance on troubleshooting steps would be greatly appreciated. I Greenslime
A high-quality scan tool is required to perform a crankshaft sensor relearn after replacement. Camshaft sensor replacement does not require a scan tool, but it's still recommended to verify functionality post-installation. The theft protection light could indicate that the anti-theft system has disabled the starter or fuel injectors, leading to no-start or stalling conditions. Check for 5-volt reference and ground integrity in the sensor circuits. Perform signal circuit continuity tests using a multimeter or test light. If wiring is confirmed as good, potential causes include a faulty crankshaft position sensor, engine oil contamination, damage to the crankshaft reluctor wheel, or wear in the timing chain, tensioner, or sprockets. If debris is found in the engine oil, inspect internal engine components for root cause. Repair or replace any worn parts as needed. With a proper scan tool, you can monitor crankshaft position counts during a bypass test and conduct detailed circuit checks on the crankshaft sensor’s hall effect component. A reliable scan tool is essential to complete the relearn process after sensor replacement.