DTC Troubleshooting: P1237 (172)
DTC P1237:
 Boost Pressure Lower Than Expected
NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.
  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 16 .
  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 16 .
Is the air cleaner element OK?
YES -
Go to Step 4 .
NO -
  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, the system is OK at this time. If the screen indicates NOT COMPLETED, go to Step 8 and recheck.
  1. Turn the ignition switch OFF.
Is the line OK?
YES -
Go to Step 12 .
NO -
  1. Disconnect the vacuum hose (A) from the turbocharger boost control solenoid valve (B), and connect a vacuum pump/gauge (C) to the solenoid.
  1. Apply vacuum to the hose.
Does it hold the vacuum?
YES -
Go to Step 14 .
NO -
  1. Reconnect all connectors and vacuum 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.
Is DTC P1237 indicated?
YES -
Check for poor connections or loose terminals at the turbocharger boost control solenoid valve and the ECM, then go to Step 1 .
NO -
Go to Step 21 .
  1. Monitor the OBD STATUS for DTC P1237 in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES -
Troubleshooting is complete. If any other Temporary DTCs or DTCs were indicated in Step 20 , go to the indicated DTC's troubleshooting.■
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 18 .