DTC P1237: Boost Pressure Lower Than Expected

1. Check for a loose or damaged these turbo control vacuum line:
   - Vacuum pump and turbocharger boost control solenoid valve
   - Turbocharger boost control solenoid valve and turbocharger boost control diaphragm
   - Vacuum pump and brake booster

Are the lines OK?

YES | - | Go to Step 2 .
NO | - | Repair or replace the damaged hoses, then go to Step 17 .

1. Check for damage or leak from intercooler and connecting hoses.

Is the intake air duct OK?

YES | - | Go to Step 3 .
NO | - | Repair or replace the damaged intake air duct, then go to Step 17 .

1. Inspect the air cleaner element.

Is the air cleaner element OK?

YES | - | Go to Step 4 .
NO | - | Replace the air cleaner element, then go to Step 17 .

1. Turn the ignition switch ON (II).

1. Clear the DTC with the HDS.

1. Start the engine. Hold the engine speed at 2,000 rpm (min −1 ) without load (in neutral) until the radiator fan comes on, then let it idle.

1. Do the TURBOCHARGER BOOST TEST in the INSPECTION MENU with the HDS.

Is the result OK?

YES | - | Go to Step 8 .
NO | - | Go to Step 10 .

1. Test-drive under these conditions:
   - Engine coolant temperature above 80 °C (176 °F)
   - Engine speed more than 3,000 rpm (min −1 )
   - Drive about 10 minutes

1. Monitor the OBD STATUS for DTC P1237 in the DTCs MENU with the HDS.

Does the screen indicate FAILED?

YES | - | Go to Step 10 .
NO | - | If the screen indicates PASSED, intermittent failure, system is OK at this time. If the screen indicates NOT COMPLETED, go to Step 8 and recheck.

1. Turn the ignition switch OFF.

1. Do the vacuum pump test.

Is the line OK?

YES | - | Go to Step 12 .
NO | - | Replace the vacuum pump, then go to Step 17 .

1. Disconnect the vacuum hose (A) from the turbocharger boost control solenoid valve (B), and connect a vacuum pump/gauge to the solenoid (B).

1. Turn the ignition switch ON (II).

1. Apply vacuum to the hose.

Does it hold the vacuum?

YES | - | Go to Step 15 .
NO | - | Replace the turbocharger boost control solenoid valve, then go to Step 17 .

1. Turn the ignition switch OFF.

1. Replace the turbocharger assembly.

1. Reconnect all connectors and hoses.

1. Turn the ignition switch ON (II).

1. Reset the ECM with the HDS.

1. Start the engine. Hold the engine speed at 2,000 rpm (min −1 ) without load (in neutral) until the radiator fan comes on, then let it idle.

1. Test-drive under these conditions:
   - Engine coolant temperature above 80 °C (176 °F)
   - Engine speed more than 3,000 rpm (min −1 )
   - Drive about 10 minutes

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

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P1237 is indicated, check for poor connections or loose terminals at the turbocharger boost control solenoid valve and the ECM, then go to Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | Go to Step 23 .

1. Monitor the OBD STATUS for DTC P1237 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES | - | Troubleshooting is complete.■
NO | - | If the screen indicates FAILED, check for poor connections or loose terminals at the turbocharger boost control solenoid valve and the ECM, then go to Step 1 . If the screen indicates NOT COMPLETED, go to Step 20 and recheck.