Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Procedures
2001 Chevrolet Cavalier LS, 2.4 TSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 Pontiac Sunfire and 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
- Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
- Observe the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC or as close to the Freeze Frame/Failure Records data that you observed. See CONDITIONS FOR RUNNING DTC . Does the DTC fail this ignition? If yes, go to next step. If no, problem is intermittent. See INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
- Turn ignition on, with engine off. Use scan tool in order to save the Freeze Frame/Failure Records data stored when the DTC set. Turn ignition off and wait 30 seconds. Disconnect PCM connector. Set Digital Multimeter (DMM) to 400 millivolts AC hertz scale. Observe frequency between the KS signal and KS low reference while tapping on the block with a non-metallic object. Does the DMM display a fluctuating frequency while tapping on the block? If yes, go to step 6 . If no, go to next step.
- Disconnect KS pigtail connector. Test for an open in knock sensor signal or low reference circuits. Did you find and correct the condition? If yes, go to step 12 . If no, go to next step.
- Inspect for a poor connection at KS pigtail harness connector. Did you find and correct the condition? If yes, go to step 12 . If no, go to step 9 .
- Test for a short to ground or a short to voltage in KS signal circuit. Did you find and correct the condition? If yes, go to step 12 . If no, go to next step.
- Test for a short to ground or short to voltage in the KS low reference circuit. Did you find and correct the condition? If yes, go to step 12 . If no, go to next step.
- Inspect for a poor connection at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step 12 . If no, go to step 10 .
- Replace knock sensor. When complete, go to step 12 .
- Inspect knock sensor and harness pigtail assembly for damage. Did you find and correct the condition? If yes, go to step 12 . If no, go to next step.
- Replace PCM. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE under PROGRAMMING. After replacing PCM, go to next step.
- Use the scan tool in order to clear the DTCs. Turn OFF ignition for 30 seconds. Start engine. Operate vehicle within the Conditions for Running in the DTC. See CONDITIONS FOR RUNNING DTC . Did the DTC Run and Pass? If yes, go to next step. If no, go to step 2 .
- Using scan tool, observe stored information and Capture Info. Does scan tool displays any undiagnosed DTCs? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
NOTE:
If an engine knock can be heard, repair engine mechanical condition before proceeding with this test.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.