P0193 Fuel Pressure Sensor High

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:

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) is above a calibrated threshold for a certain period of time.

Possible Causes

5-VOLT SUPPLY CIRCUIT SHORTED TO VOLTAGE
FRP SENSOR SIGNAL 1 CIRCUIT SHORTED TO VOLTAGE
FRP SENSOR SIGNAL 2 CIRCUIT SHORTED TO VOLTAGE
FRP SENSOR SIGNAL 1 CIRCUIT OPEN/HIGH RESISTANCE
FRP SENSOR SIGNAL 2 CIRCUIT OPEN/HIGH RESISTANCE
FRP SENSOR SIGNAL 1 CIRCUIT SHORTED TO THE 5-VOLT SUPPLY CIRCUIT
FRP SENSOR SIGNAL 2 CIRCUIT SHORTED TO THE 5-VOLT SUPPLY CIRCUIT
SENSOR RETURN OPEN/HIGH RESISTANCE
FUEL RAIL PRESSURE 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 there are any 5-Volt supply DTCs present, repair those DTCs before proceeding.
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 (K181) FRP SENSOR SIGNAL 1 CIRCUIT FOR A SHORT TO VOLTAGE

1. Turn the ignition off.
2. Disconnect the Fuel Rail Pressure Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (K181) FRP Sensor Signal 1 circuit at the FRP Sensor harness connector. Is the reading above 5.2 volts?

Yes
• Repair the (K181) Fuel Rail Pressure Sensor Signal 1 circuit for a short to voltage.
• 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 FOR THE (K181) FRP SENSOR SIGNAL 1 CIRCUIT SHORTED TO THE (K350) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnected PCM C1 harness connector.
3. Measure the resistance between the (K181) FRP Sensor Signal 1 circuit and the (K350) 5-Volt Supply 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 the (K350) 5-Volt Supply circuit.
• 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 THE (K181) FRP SENSOR SIGNAL 1 CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K181) FRP Sensor Signal 1 circuit between the FRP Sensor harness connector and the PCM C1 harness connector. Is the resistance below 5.0 Ohms?

Yes
• Go To 5

No
• Repair the (K181) Fuel Rail Pressure Sensor Signal 1 circuit for an open or high resistance.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

5. CHECK THE (K179) FRP SENSOR 2 SIGNAL CIRCUIT FOR A SHORT TO VOLTAGE
1. Turn the ignition off.
2. Disconnect the Fuel Rail Pressure Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (K179) FRP Sensor 2 Signal circuit at the FRP Sensor harness connector. Is the reading above 5.2 volts?

Yes
• Repair the (K179) Fuel Rail Pressure Sensor Signal 2 circuit for a short to voltage.
• 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 (K350) 5-VOLT SUPPLY CIRCUIT
1. Turn the ignition off.
2. Disconnected PCM C1 harness connector.
3. Measure the resistance between the (K179) FRP Sensor Signal 2 circuit and the (K350) 5-Volt Supply circuit at the FRP Sensor harness connector.
Is the resistance below 10k Ohms?

Yes
• Repair the short between the (K179) Fuel Rail Pressure Sensor 2 Signal circuit and the (K350) 5-Volt Supply 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 (K179) FRP SENSOR SIGNAL 2 CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K179) FRP Sensor Signal 2 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 (K1791) Fuel Rail Pressure Sensor Signal 2 circuit for an open or high resistance.
• Perform the POWERTRAIN VERIFICATION TEST - 6.7L. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

8. CHECK THE (K180) SENSOR RETURN 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 9

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

9. CHECK THE FUEL RAIL PRESSURE SENSOR
1. Turn the ignition off.
2. Reconnect the PCM C1 harness connector.
3. Reconnect the FRP Sensor harness connector.
4. Turn the ignition on.
5. With the scan tool, erase DTCs.
6. While monitoring scan tool, connect a jumper between the (K181) FRP Sensor Signal 1 circuit and the
(K180) Sensor Return circuit at the FRP Sensor harness connector. Does the DTC P0192 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 10

10. 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).