DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P1128

DTC P1128 : MAP Sensor Signal Lower Than Expected

NOTE:
* Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information How To Troubleshoot The Fuel And Emissions Systems.
* Before you begin, check for poor connections or a blockage at the intake air duct.

1. MAP sensor performance check:

MAP sensor performance check
-1. Turn the ignition switch to ON (II).

-2. Check the MAP SENSOR in the DATA LIST with the HDS.

Is less than 54.1 kPa (16.0 inHg, 406 mmHg) or 1.61 V held for more than 5 seconds?
-YES- Replace the MAP sensor Service and Repair, then do the repair verification.
-NO- Go to step 2.

2. Problem verification:

Problem verification
-1. Clear the DTC with the HDS.

-2. 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.

-3. Test-drive under these conditions:
* Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
* Engine speed between 1,000-4,000 rpm
* A/T in D, M/T in 3rd
* Vehicle speed accelerated from 16 to 31 mph (25 to 50 km/h) under half throttle

-4. Monitor the OBD STATUS for DTC P1128 in the DTCs MENU with the HDS.

Does the HDS indicate FAILED?
-YES- The failure is duplicated. Replace the MAP sensor Service and Repair, then do the repair verification.
-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 2-2 and recheck.

Repair verification (OBD STATUS check):

-1. Turn the ignition switch to ON (II).

-2. Reset the ECM/PCM with the HDS How To Troubleshoot The Fuel And Emissions Systems.

-3. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.

-4. 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.

-5. Test-drive under these conditions:
* Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
* Engine speed between 1,000-4,000 rpm
* A/T in D, M/T in 3rd
* Vehicle speed accelerated from 16 to 31 mph (25 to 50 km/h) under half throttle

-6. Monitor the OBD STATUS for DTC P1128 in the DTCs MENU with the HDS.

Does the HDS indicate PASSED, FAILED, or NOT COMPLETED?
-PASSED- Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated, go to the indicated DTC's troubleshooting.
-FAILED- Go to step 1 and recheck.
-NOT COMPLETED- Meet the test condition, and check the OBD STATUS again.