DTC Troubleshooting

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.

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 parts with vacuum leaks, then go to step 9.

NO - Go to step 2.

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

Is more than 36.9 kPa (11.0 in.Hg, 277 mmHg) or 1.1 V held for more than for 5 seconds?

YES - Go to step 7.

NO - Go to step 4.

4. Clear the DTC with the HDS.
5. Test- drive under these conditions:
- ECT SENSOR 1 above 158 °F (70 °C)
- A/T in D position (M/T in 5th gear)
- Drive at a steady speed between 55 - 75 mph (88 - 120 km/h) for 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 2 seconds

6. Monitor the OBD STATUS for DTC P1129 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, 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 5 and recheck.

7. Turn the ignition switch OFF.
8. Replace the MAP sensor.
9. Turn the ignition switch ON (II).
10. Reset the ECM/PCM with the HDS.
11. Do the ECM/PCM idle learn procedure.
12. 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.
13. Test- drive under these conditions:
- ECT SENSOR 1 above 158 °F (70 °C)
- A/T in D position (M/T in 5th gear)
- Drive at a steady speed between 55 - 75 mph (88 - 120 km/h) for 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 2 seconds

14. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1129 indicated?

YES - Check for poor connections or loose terminals at the MAP sensor and the ECM/PCM, then go to step 1.

NO - If Temporary DTC or DTC P1129 is not indicated, or if any other Temporary DTCs or DTCs are indicated, go to step 15.

15. Monitor the OBD STATUS for DTC P1129 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - If there was no Temporary DTCs or DTCs indicated on step 14, troubleshooting is complete. If any other Temporary DTCs or DTCs was indicated on step 14, go to the indicated DTC's 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 and recheck.