DTC P1128: MAP Sensor Signal Lower Than Expected
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).
- Before starting this troubleshooting check for poor connections or blockage at the intake air duct.
- Turn the ignition switch ON (II).
- Check the MAP SENSOR in the DATA LIST with the HDS.
Is less than 54.1 kPa (16.0 in.Hg, 406 mmHg) or 1.61 V held for more than 5 seconds?
YES - Go to step 7.
NO - Go to step 3.
- Clear the DTC with the HDS.
- Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158°F (70°C)
- Engine speed between 1,400-5,400 rpm
- A/T in D position (M/T in 3rd gear)
- Vehicle speed accelerated from 16-31 mph (25-50 km/h) under half throttle
- Monitor the OBD STATUS for DTC P1128 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES - Go to step 7.
NO - If the screen indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the MAP sensor and the ECM/PCM. If the screen indicates NOT COMPLETED, go to step 4 and recheck.
- Turn the ignition switch OFF.
- Replace the MAP sensor (see MAP SENSOR REPLACEMENT ).
- Turn the ignition switch ON (II).
- Reset the ECM/PCM with the HDS.
- Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).
- Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.
- Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158°F (70°C)
- Engine speed between 1,400-5,400 rpm
- A/T in D position (M/T in 3rd gear)
- Vehicle speed accelerated from 16-31 mph (25-50 km/h) under half throttle
- Check for Temporary DTCs or DTCs with the HDS.
Is DTC P1128 indicated?
YES - Check for poor connections or loose terminals at the MAP sensor and the ECM/PCM, then go to step 1.
NO - Go to step 15.
- Monitor the OBD STATUS for DTC P1128 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES - Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in step 14, go to the indicated DTCs troubleshooting.
NO - If the screen indicates FAILED, check for poor connections or loose terminals at the MAP sensor and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 12.