DTC P1128: MAP Sensor Signal Lower Than Expected
- Before you troubleshoot, record all freeze data and any on-board snapshot, and review GENERAL TROUBLESHOOTING INFORMATION .
- Before starting this troubleshooting check for poor connections or a blockage at the intake air duct.
- Turn the ignition switch to 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 (A/T in P or N, M/T in 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, M/T in 3rd
- 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 HDS 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 HDS indicates NOT COMPLETED, go to step 4 and recheck.
- Turn the ignition switch to LOCK (0).
- Replace the MAP sensor (see MAF SENSOR/IAT SENSOR REPLACEMENT ).
- Turn the ignition switch to ON (II).
- Reset the ECM/PCM with the HDS.
- Do ECM/PCM IDLE LEARN PROCEDURE .
- Start the engine. Hold the engine speed at 3, 000 rpm without load (A/T in P or N, M/T in 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, M/T in 3rd
- Vehicle speed accelerated from 16-31 mph (25-50 km/h) under half throttle
- Check for Pending or Confirmed 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 Pending or Confirmed DTCs were indicated in step 14, go to the indicated DTC's troubleshooting.
NO: If the HDS indicates FAILED, check for poor connections or loose terminals at the MAP sensor arid the ECM/PCM, then go to step 1. If the HDS indicates NOT COMPLETED, go to step 12.