P0191

DTC P0191: Fuel Rail Pressure Sensor Circuit Range/performance Problem

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Turn the ignition switch OFF.
2. Check for a loose or damaged fuel pressure regulator P1 vacuum line.

Is the line OK?

YES - Go to step 3.

NO - Reconnect or repair the fuel pressure regulator PI vacuum line, then go to step 21.

3. Check the fuel system for any leaking parts.

Are any parts leaking?

YES - Replace the leaking part(s), then go to step 21.

NO - Go to step 4.

4. 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.
5. Test-drive the vehicle for several minutes in the range of these recorded on-board snapshot parameters:
- ENGINE SPEED
- MAP SENSOR

6. Monitor the OBD STATUS for DTC P0191 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, the system is OK at this time. Check for poor connections or loose terminals at the fuel rail pressure sensor and the PCM. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 4 and recheck.

7. 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.
8. Snap the throttle to an engine speed of 3,000 rpm or more.
9. Check the FUEL RAIL PRESSURE SENSOR in the DATA LIST with the HDS while snapping the throttle.

Does the reading change 4 kPa (0.58 psi, 0.04 kgf/sq.cm) or more?

YES - Go to step 10.

NO - Replace the fuel rail pressure sensor, then go to step 19.

10. Check the FUEL RAIL PRESSURE SENSOR in the DATA LIST with the HDS at idle.

Is about 204-326 kPa (29.58- 47.3 psi, 2.08- 3.32 kgf/sq.cm) indicated?

YES - Go to step 16.

NO - Go to step 11.

11. Turn the ignition switch OFF.
12. Remove the fuel rail pressure sensor.
13. Reconnect the fuel rail pressure sensor 3P connector to the sensor.
14. Turn the ignition switch ON (II).
15. Compare the value of the BAR0 SENSOR and the FUEL RAIL PRESSURE SENSOR in the DATA LIST with the HDS.

Does the reading differ 22.3 kPa (3.23 psi, 0.23 kgf/sq.cm) or more?

YES - Replace the fuel rail pressure sensor, then go to step 19.

NO - Replace the fuel pressure regulator P1, then go to step 19.

16. Check the MAP SENSOR in the DATA LIST with the HDS.

Is about 53.2 kPa (15.7 in.Hg, 399 mmHg), or 1.59 V or more indicated?

YES - Go to step 17.

NO - Replace the MAP sensor, then go to step 19.

17. Start the engine.
18. Check the MAP SENSOR in the DATA LIST with the HDS while snapping the throttle to fuel cut engine speed.

Is about 36.9 kPa (10.9 in.Hg, 277 mmHg), or 1.51 V or less indicated?

YES - Check for poor connections or loose terminals at the fuel rail pressure sensor and the PCM. Also check for a loose or damage fuel pressure regulator P1 vacuum line. Then go to step 19.

NO - Replace the MAP sensor, then go to step 19.

19. Turn the ignition switch OFF.
20. Reconnect all connectors.
21. Turn the ignition switch ON (II).
22. Reset the PCM with the HDS.
23. Do the PCM idle learn procedure.
24. Test-drive the vehicle for several minutes in the range of these recorded on-board snapshot parameters:
- ENGINE SPEED
- MAP SENSOR

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

Is DTC P0191 indicated?

YES - Check for poor connections or loose terminals at the fuel rail pressure sensor and the PCM, then go to step 1.

NO - Go to step 26.

26. Monitor the OBD STATUS for DTC P0191 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 25, go to the indicated DTC's troubleshooting.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the fuel rail pressure sensor and the PCM, then go to step 1. If the screen indicates EXECUTING, keep driving until a result comes on. If the screen indicates OUT OF CONDITION, go to step 23.