DTC P1128: MAP Sensor Circuit Lower Than Expected

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information (see GENERAL TROUBLESHOOTING INFORMATION ).

Inspect the air cleaner element (see AIR CLEANER ELEMENT INSPECTION/REPLACEMENT ).
Is there damage or clogging?
1. YES- Replace the air cleaner element (see AIR CLEANER ELEMENT INSPECTION/REPLACEMENT ). Then clear the DTC with the HDS, and go to step 13.
2. NO- Go to step 2.
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?
1. YES- Go to step 7.
2. NO- Go to step 4.
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:
- ECT SENSOR above 158°F (70°C)
- A/T in D position (M/T in 3rd gear)
- Vehicle speed above 15 mph (24 km/h)
- Engine speed between 1,400 and 5,700 RPM for 2 seconds or more
Monitor the OBD STATUS for DTC P1128 in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
1. YES- Go to step 8.
2. NO- If the screen indicates PASSED, intermittent failure, system is OK at this time. If the screen indicates NOT COMPLETED, go to step 5 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:
- ECT SENSOR above 158°F (70°C)
- A/T in D position (M/T in 3rd gear)
- Vehicle speed above 15 mph (24 km/h)
- Engine speed between 1,400 and 5,700 RPM for 2 seconds or more
Check for Temporary DTCs or DTCs with the HDS.
Are any Temporary DTCs or DTCs indicated?
1. YES- If DTC P1128 is indicated, check for poor connections or loose terminals at the MAP sensor and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
2. NO- Go to step 16.
Monitor the OBD STATUS for DTC P1128 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
1. YES- Troubleshooting is complete.
2. 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 14 and recheck.