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Detroit Fault Codes SPN 94/FMI 4 – EPA10 – GHG14

06/04/2026
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SPN 94/FMI 4 - EPA10 – GHG14
Low Side Fuel Pressure Sensor Circuit Failed Low
SPN 94/FMI 4
Description Low Side Fuel Pressure Sensor Circuit Short to Ground
Monitored Parameter Low Side Fuel Pressure Sensor Circuit
Typical Enabling Conditions Always Enabled
Monitor Sequence None
Execution Frequency Always Enabled
Typical Duration Two Seconds
Dash Lamps MIL, CEL
Engine Reaction None
Verification Engine Idle (One minute)
SPN 94/FMI 4 - EPA10 – GHG14

Check as follows:

Warning
PERSONAL INJURY
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked.
Warning
PERSONAL INJURY
Diesel engine exhaust and some of its constituents are known to the State of California to cause cancer, birth defects, and other reproductive harm.
  • Always start and operate an engine in a well ventilated area.
  • If operating an engine in an enclosed area, vent the exhaust to the outside.
  • Do not modify or tamper with the exhaust system or emission control system.
1. Connect DiagnosticLink® .
2. Turn the ignition ON (key ON, engine OFF).
3. Check for multiple codes. Are the following codes also present?
  • SPN 411/FMI 4
  • SPN 51/FMI 4
  • SPN 94/FMI 4
3.1. Yes; repair open 5V supply between pin 117 of the Motor Control Module (MCM) 120- pin connector and the Low Pressure Pump Output (LPPO) fuel pressure sensor, EGR delta P sensor, and the intake throttle harness connectors. Clear codes. Verify repairs.
3.2. No; Go to step 4.
4. Disconnect the LPPO sensor.
5. Inspect the LPPO sensor harness connector for signs of damaged, bent, spread, corroded or unseated (pushed out) pins and signs of moisture in the connector or wire damage near the connector. Is damage present?
5.1. Yes; repair as necessary.Go to step 14.
5.2. No; Go to step 6.
6. Measure the voltage between pins 3 and 2 of the LPPO sensor harness side connector (5V supply from MCM) and (ground circuit to MCM). Is the voltage greater than 4.5 volts?
6.1. Yes; Go to step 8.
6.2. No; Go to step 7.
7. Measure the voltage between pin 3 of the LPPO sensor harness side connector (5V supply from MCM) and ground (battery ground lug by starter). Is the voltage greater than 4.5 volts?
7.1. Yes; repair open wire between pin 102 of the MCM 120-pin connector and the Oil Separator speed sensor, Intake Manifold Pressure/Temperature sensor, and the LPPO sensor harness connectors. Go to step 14.
7.2. No; repair open wire between pin 117 of the MCM 120-pin connector and the EGR delta P sensor, intake throttle, and LPPO sensor harness connectors. Go to step 14.
8. Turn the ignition OFF.
9. Disconnect the MCM 120-pin connector.
10. Inspect the MCM harness connector for signs of damaged, bent, spread, corroded or unseated (pushed out) pins and signs of moisture in the connector or wire damage near the connector. Is damage present?
10.1. Yes; repair as necessary. Go to step 14.
10.2. No; Go to step 11.
11. Measure the resistance between (signal circuit) pin 113 from MCM harness connector to pin 1 of the LPPO sensor harness connector. Is the resistance less than five ohms?
11.1. Yes; Go to step 12.
11.2. No; repair open wire between pin 113 of the MCM 120-pin harness side connector and the LPPO sensor harness side connector.Go to step 14.
12. Measure the resistance between pins 1 and 2 of the LPPO sensor harness connector (signal and ground circuits). Is the resistance less than 10K ohms?
12.1. Yes; repair short between pins 113 and 102 of the MCM 120-pin harness side connector and the LPPO sensor harness side connector. Go to step 14.
12.2. No; Go to step 13.
13. Measure the resistance between pin 1 of the LPPO sensor harness side connector (signal circuit) and ground (battery ground lug by starter). Is the resistance less than 10K ohms?
13.1. Yes; repair short to ground between pin 113 of the MCM 120-pin harness side connector and the LPPO sensor harness side connector. Go to step 14.
13.2. No; replace the LPPO sensor. Refer to section “Removal of the Low Pressure Fuel Sensor – Two-Filter System” . Go to step 14.
14. Clear codes and verify repairs. If fault returns, install a test MCM and retest. If code does not return, replace MCM. Refer to section “Removal of the Motor Control Module” . Verify repairs.

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