P0093 - Fuel System Leak Detected - Large Leak

Theory of Operation

The Powertrain Control Module (PCM) determines that there is a leak in the Low Pressure Fuel Delivery
system based on inputs from the High Pressure Fuel system, Fuel Tank Level Signal, Emissions systems, and
other engine conditions. The PCM will turn on the MIL on after this diagnostic runs and fails for two consecutive
drive cycles. This DTC will cause active regeneration to be disabled.

When Monitored and Set Conditions

When Monitored: This diagnostic runs continuously when the following conditions are met:
• With the engine running.

Set Conditions:
• The Powertrain Control Module (PCM) has detected a leak in the Low Pressure Fuel system.

Default Actions:
• The MIL is illuminated.

Possible Causes

PRESSURE LIMITING VALVE
FUEL LEAK IN THE LOW PRESSURE FUEL DELIVERY SYSTEM
POWERTRAIN CONTROL MODULE (PCM)
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTCBased Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Diagnostic Test

1. OTHER DTCS

1. Turn the ignition on, engine not running.
2. With the scan tool, read DTCs. 

Are any other injector/fuel pressure related DTCs present?

Yes
• Diagnose and repair all other injectors/fuel pressure related DTCs before performing this diagnostic tree.

No

• Go To 2

2. ACTIVE DTC

1. With the scan tool, record all Freeze frame data.
2. With the scan tool, erase DTCs.
3. Turn the ignition off for 75 seconds.
4. Operate the engine until the coolant temperature is above 82.2°C (180°F).
5. With the scan tool, read DTCs.
Did DTC P0093 reset?

Yes
• Go To 3

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

3. EXTERNAL FUEL LEAKS

1. Put on personal protective equipment.
2. Operate engine at idle when looking for fuel leaks.
3. Use the scan tool to operate engine at a variety of engine speeds.

Any external leaks detected?

Yes
• Repair or replace component with external fuel leak.
• 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 FUEL DELIVERY SYSTEM

1. (Refer to 29 - Non-DTC Diagnostics/Drivability - Diesel - Diagnosis and Testing) and perform the CHECKING THE FUEL DELIVERY SYSTEM diagnostic procedure.
Were any problems found?

Yes
• Repair as necessary.

No
• Go To 5

5. 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 andthe 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).