P0192 Fuel Pressure Sensor Low

Theory of Operation

The Powertrain Control Module (PCM) provides the Fuel Rail Pressure Sensor with a 5-Volt supply and sensor ground, and receives a signal voltage back from the Fuel Rail Pressure Sensor. This sensor signal voltage changes based on the pressure in the fuel rail. The PCM will light the MIL lamp immediately after the diagnostic runs and fails. During this time the customer may experience a power and or speed derate. The PCM will turn off the MIL light after the diagnostic runs and passes in four consecutive drive cycles.

When Monitored and Set Conditions

• When Monitored:

With the ignition on and battery voltage greater than 10.4 Volts.

Set Condition:

One or both of the Fuel Rail Pressure Sensor Signals to the Powertrain Control Module (PCM) falls
below a calibrated threshold for a certain period of time.

Possible Causes

FRP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
FRP SENSOR SIGNAL CIRCUIT SHORTED TO THE SENSOR RETURN
FRP SENSOR RETURN CIRCUIT OPEN/HIGH RESISTANCE
FRP SENSOR
POWERTRAIN CONTROL MODULE (PCM)
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-
Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Diagnostic Test

1. ACTIVE DTC

NOTE: If a 5-Volt reference DTC is present, repair that DTC before proceeding with this test.
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.
Did the DTC reset?

Yes
• Go To 2

No
• Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

2. CHECK THE FUEL PRESSURE SENSOR

1. Turn the ignition off.
2. Disconnect the FRP Sensor harness connector.
3. Turn the ignition on. Does the DTC P0193 set?

Yes
• Replace the Fuel Rail Pressure Sensor in accordance with the Service Information.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Go To 3

3. CHECK THE (K181) FRP SENSOR SIGNAL 1 CIRCUIT FOR A SHORT TO GROUND

1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector. NOTE: Check connectors - Clean/repair as necessary.
3. Measure the resistance between ground and the (K181) FRP Sensor Signal 1 circuit in the FRP Sensor harness connector.
Is the resistance below 10k Ohms?

Yes
• Repair the (K181) Fuel Rail Pressure Sensor Signal 1 circuit for a short to ground.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Go To 4

4. CHECK FOR THE (K181) FRP SENSOR SIGNAL CIRCUIT SHORTED TO THE (K180) SENSOR RETURN

1. Measure the resistance between the (K181) FRP Sensor Signal 1 circuit and (K180) Sensor Return circuit at the FRP Sensor harness connector.
Is the resistance below 10k Ohms?

Yes
• Repair the short between the (K181) Fuel Rail Pressure Sensor Signal 1 circuit and (K180) Sensor Return circuit.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Go To 5

5. CHECK THE (K179) FRP SENSOR SIGNAL 2 CIRCUIT FOR A SHORT TO GROUND
1. Turn the ignition off.
2. Disconnect the PCM C1 harness connector. NOTE: Check connectors - Clean/repair as necessary.
3. Measure the resistance between ground and the (K179) FRP Sensor Signal 2 circuit in the FRP Sensor harness connector. Is the resistance below 10k Ohms?

Yes
• Repair the (K179) Fuel Rail Pressure Sensor Signal 2 circuit for a short to ground.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based
Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
 

No
• Go To 6

6. CHECK FOR THE (K179) FRP SENSOR SIGNAL 2 CIRCUIT SHORTED TO THE (K180) SENSOR RETURN

1. Measure the resistance between the (K179) FRP Sensor Signal 2 circuit and (K180) Sensor Return circuit at the FRP Sensor harness connector.
Is the resistance below 10k Ohms?
 

Yes
• Repair the short between the (K179) Fuel Rail Pressure Sensor Signal 2 circuit and (K180) Sensor Return circuit.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
 

No
• Go To 7

7. CHECK THE (K180) SENSOR RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K180) Sensor Return circuit between the FRP Sensor harness connector and the PCM C1 harness connector.
Is the resistance below 5.0 Ohms?

Yes
• Go To 8

No
• Repair the (K180) Sensor Return circuit for an open circuit or high resistance.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

8. POWERTRAIN CONTROL MODULE
1. Disconnect all PCM harness connectors.
2. Disconnect all related in-line harness connections (if equipped).
3. Disconnect the related component harness connectors.
4. Inspect harness connectors, component connectors, and all male and female terminals for the following
conditions:

• Proper connector installation.
• Damaged connector locks.
• Corrosion.
• Other signs of water intrusion.
• Weather seal damage (if equipped).
• Bent terminals.
• Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
• Terminals that have been pushed back into the connector cavity.
• Perform a terminal drag test on each connector terminal to verify proper terminal tension.
• Repair any conditions that are found.

5. Reconnect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
6. Reconnect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
7. Reconnect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. With the scan tool, erase DTCs.
9. Using the recorded Freeze Frame and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
10. With the scan tool, read PCM DTCs.
Did the DTC return?

Yes
• Replace the Powertrain Control Module (PCM) in accordance with the Service Information. (Refer to 08 - Electrical/8E - Electronic Control Modules/MODULE, Powertrain Control/Removal) .
• Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
• Test complete.
• Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).