DTC P0238: MAP SENSOR VOLTAGE TOO HIGH
Monitor & Set Conditions
Manifold Air Pressure (MAP) sensor voltage is monitored when engine speed is greater than 400 RPM but less than 3520 RPM and battery voltage is greater than 10.4 volts. DTC may be stored if Engine Control Module (ECM) senses MAP sensor signal voltage is greater than 4.88 volts at engine start-up or with engine running for 2 seconds.
Possible Causes
- Intake Air Temperature (IAT) Or Engine Coolant Temperature (ECT) Codes
- Oil Pressure Sensor Too High Or 5-volt Supply Codes
- Intermittent Wiring Problem
- Boost Pressure Sensor
- MAP Sensor Signal Circuit Shorted To Voltage
- Sensor Ground Circuit Open
- MAP Sensor Signal Circuit Open
- MAP Sensor
- ECM
Testing
1. Turn ignition on with engine off. Using DRBIII(R) scan tool, check for engine DTCs. If DTC P0113 or P0118 exists, perform DTC P0113: INTAKE AIR TEMPERATURE SENSOR VOLTAGE TOO HIGH or DTC P0118: ENGINE COOLANT TEMPERATURE SENSOR VOLTAGE TOO HIGH test. If these DTC do not exist, go to next step.
2. Ensure ignition is on with engine off. Using scan tool, check for engine DTCs. If no SENSOR SUPPLY VOLTAGE TOO HIGH or OIL PRESSURE SENSOR VOLTAGE TOO HIGH DTCs exist, go to next step. If any SENSOR SUPPLY VOLTAGE TOO HIGH or OIL PRESSURE SENSOR VOLTAGE TOO HIGH DTCs exist, perform appropriate test for specified DTC. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
3. Ensure ignition is on with engine off. Using scan tool, read MAP sensor voltage. If MAP sensor voltage is less than 5.5 volts, go to next step. If MAP sensor voltage is 5.5 volts or greater, go to step 5 .
4. Ensure ignition is on with engine off. Using scan tool, read MAP sensor voltage while wiggling wiring harness and connectors between MAP sensor and ECM. MAP sensor is located on driver's side rear corner of cylinder head. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector. If MAP sensor voltage goes to greater than 4.6 volts while wiggling wiring harness and/or connectors, repair wiring or connectors as necessary. If MAP sensor voltage does not go to greater than 4.6 volts while wiggling wiring harness and connectors, test is complete.
5. Turn ignition off. Perform turbocharger boost pressure test. See TURBOCHARGER under AIR INDUCTION SYSTEMS in SYSTEM & COMPONENT TESTING - RAM PICKUP - DIESEL article. If boost pressure test passes, go to next step. If boost pressure test does not pass, repair as necessary.
6. Ensure ignition is off. Disconnect MAP sensor harness connector. MAP sensor is located on driver's side rear corner of cylinder head. Turn ignition on with engine off. Using DVOM, measure voltage between ground and terminal No. 2 (Gray/Red wire) on MAP sensor harness connector. If voltage is 5.5 volts or less, go to next step. If voltage is greater than 5.5 volts, repair short to voltage on Gray/Red wire between MAP sensor and ECM. ECM is located on driver's side of engine, just in front of fuel transfer pump and contains a 50-pin connector.
7. Turn ignition off. Ensure MAP sensor harness connector is still disconnected. Disconnect ECM harness connector. Using DVOM, measure resistance of Black/Light Blue wire between terminal No. 3 on MAP sensor harness connector and terminal No. 11 on ECM harness connector. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or greater, repair open in Black/Light Blue wire between MAP sensor and ECM.
8. Ensure ignition is still off. Ensure MAP sensor harness connector and ECM harness connector are still disconnected. Using DVOM, measure resistance of Gray/Red wire between terminal No. 2 on MAP sensor harness connector and terminal No. 8 on ECM harness connector. If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or greater, repair open in Gray/Red wire between MAP sensor and ECM.
9. Ensure ignition is off. Reinstall ECM harness connector. Ensure MAP sensor harness connector is still disconnected. Connect jumper wire between terminals No. 2 (Gray/Red wire) and No. 3 (Black/Light Blue wire) on MAP sensor harness connector. Turn ignition on. Using scan tool, read MAP sensor voltage. If MAP sensor voltage is less than one volt, remove jumper wire and replace MAP sensor. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. If MAP sensor voltage is one volt or greater, remove jumper wire and replace and program the ECM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article.
