DTC Troubleshooting

Control System DTCs

DTC Troubleshooting: P1129

DTC P1129 : MAP Sensor Signal Higher 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.

1. Vacuum leak check:

Vacuum leak check
-1. Check for vacuum leaks in these parts:
* PCV valve
* PCV hose
* EVAP canister purge valve
* Throttle body
* Intake manifold
* Brake booster
* Brake booster hose

Are there any vacuum leaks?
-YES- Repair or replace the parts with vacuum leaks, then do the repair verification.
-NO- Go to step 2.

2. MAP sensor performance check:

MAP sensor performance check
-1. Start the engine. Hold the engine speed at 3,000 rpm without load (in neutral) until the radiator fan comes on, then let it idle.

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

Is more than 36.9 kPa (11.0 inHg, 277 mmHg) or 1.1 V held for more than for 5 seconds?
-YES- Replace the MAP sensor Service and Repair, then do the repair verification.
-NO- Go to step 3.

3. Problem verification:

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

-2. Test-drive under these conditions:
* Engine coolant temperature (ECT SENSOR 1) above 158 °F (70 °C)
* Engine speed between 1,400-6,800 rpm
* Transmission in 5th
* Drive at a steady speed between 55-75 mph (88-120 km/h) for 10 seconds, then decelerate (with the throttle fully closed) for 5 seconds

-3. Monitor the OBD STATUS for DTC P1129 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. If the HDS indicates NOT COMPLETED, go to step 3-2 and recheck.

Repair verification (OBD STATUS check):

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

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

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

-4. Start the engine. Hold the engine speed at 3,000 rpm without load (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 1,400-6,800 rpm
* Transmission in 5th
* Drive at a steady speed between 55-75 mph (88-120 km/h) for 10 seconds, then decelerate (with the throttle fully closed) for 5 seconds

-6. Monitor the OBD STATUS for DTC P1129 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.