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 Procedure
2001 Chevrolet Cavalier LS, 2.4 TSECTION Diagnostic Procedure
WARNING: This page is about a different car, the 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.
- Turn ignition on. Using scan tool, establish communication with AF ECM. Observe and record MAP sensor kPa display. MAP sensor kPa reading should be 75 kPa at altitude or 95 kPa at sea level. Is the value greater than the value shown? If yes, go to next step. If no, go to step 7 .
- Remove vacuum line from MAP sensor. Connect Hand Vacuum Pump (J-23738-A) to MAP sensor. Slowly apply vacuum one in. Hg at a time. Monitor MAP sensor kPa display on scan tool. Each one inch of vacuum should result in a 3 to 4 kPa drop in MAP sensor kPa reading. Observe MAP sensor kPa reading for a skip or jump while increasing vacuum up to 20 in. Hg. Did you observe a skip or jump? If yes, go to step 7 . If no, go to next step.
- Monitor MAP sensor kPa reading with 20 in. Hg of vacuum applied. MAP sensor kPa reading should be 34 kPa. If yes, go to next step. If no, go to step 7 .
- Disconnect MAP sensor from hand vacuum pump. If MAP sensor kPa reading is more than 75 kPa at altitude or 95 kPa at sea level, go to next step. If MAP sensor kPa readings is less than 75 kPa at altitude or 95 kPa at sea level, go to step 7 .
- Fault is not present at this time. Are any DTCs stored that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, problem is intermittent. Refer to INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM.
- Inspect for proper terminal contact. Inspect the MAP sensor ground circuit for an open or high resistance between the MAP sensor connector and the PCM connector terminal. Did you find a problem? If yes, go to next step. If no, go to step 9 .
- Repair connections or circuit as necessary. Is the action complete? If yes, go to step 10 .
- Replace MAP sensor. See MANIFOLD ABSOLUTE PRESSURE SENSOR in appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to next step.
- Using scan tool, clear DTCs. Start engine. Allow engine to idle until engine reaches normal operating temperature. Select DTC and Specific DTC function. Enter DTC number which was set. Operate vehicle within the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran. See CONDITIONS FOR SETTING DTC . Does scan tool indicate the diagnostic passed? If yes, system is okay. If no, go to step 2 .
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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.