CAT Engine 944 Fault Code: Fuel Pressure short to ground
Also called Fuel Delivery Pressure Sensor : Voltage Below Normal, Fuel Pressure Short to Ground
Fuel Pressure short to ground · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 944 (SPN 94, FMI 4) means the ECM detected fuel delivery pressure sensor signal voltage below normal for eight seconds after the ECM had been powered for two seconds. The ECM logs the code, sets the fuel pressure parameter to a gauge pressure of zero, and flags fuel pressure data as invalid, using a default value in its place. Caterpillar reports no performance effects from this fault, but a bad fuel pressure reading can still hide a real fuel delivery problem, so it needs to be checked out.
Medium severity. Caterpillar states there are no direct performance effects when this code is active, since the ECM substitutes a default value for fuel pressure. However, running with an invalid fuel pressure signal means the engine loses a real diagnostic input, so this should be diagnosed within the shift rather than ignored long term.
What does CAT Engine error code 944 mean?
Code 944 relates to the fuel delivery pressure sensor circuit on C10 through C32 CAT engines. This sensor tells the ECM how much pressure is present in the fuel delivery system, which the ECM uses to help manage fueling and monitor system health.
When the ECM sees signal voltage below normal on this circuit for eight seconds (after being powered for two seconds), it logs code 944, sets the pressure value to a gauge pressure of zero, and marks the fuel pressure reading as invalid. A default value is substituted so the engine keeps running.
Caterpillar's documentation for this fault repeatedly notes there are no performance effects tied to the code itself. That does not mean the underlying wiring, connector, or sensor problem is harmless, only that the ECM's fallback handling keeps the engine operating normally in the short term.
What triggers a CAT Engine 944 code?
The ECM sets this code when it detects signal voltage below normal on the fuel delivery pressure sensor circuit for eight seconds, provided the ECM has already been powered for two seconds.
Common causes of 944
- Damaged, corroded, or loose connectors or wiring in the fuel pressure sensor circuit
- General problem within the wiring harness between the ECM and the sensor
- Seals out of place at the sensor or connector
- Intermittent electrical problem in the circuit
- Faulty fuel delivery pressure sensor that needs to be replaced
- Faulty ECM that needs to be replaced
How to troubleshoot CAT Engine 944: first checks
- Inspect the fuel pressure sensor connector and surrounding harness for corrosion, abrasion, pinch points, or loose pins
- Check that connector seals are properly seated and not displaced or damaged
- Wiggle-test the harness between the ECM and the sensor while watching for the code to reset, to help catch an intermittent fault
- Verify the sensor is seated and wired correctly, then inspect the sensor itself for visible damage
- If wiring and connectors check out, test or swap the fuel pressure sensor before considering ECM replacement
How the code clears
No separate clearing step is listed. Once the underlying wiring, connector, sensor, or ECM issue is repaired and signal voltage returns to normal, the code should stop being logged on subsequent operation. Caterpillar's documentation does not describe a manual reset procedure beyond fixing the fault condition.
Affected models and serial ranges
944 appears in our records across 8 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C10 | Serial range not listed in source records |
| C11 | Serial range not listed in source records |
| C12 | Serial range not listed in source records |
| C13 | Serial range not listed in source records |
| C15 | Serial range not listed in source records |
| C16 | Serial range not listed in source records |
| C27 | Serial range not listed in source records |
| C32 | Serial range not listed in source records |
Frequently asked questions
What does CAT fault code 944 mean?
It means the ECM detected fuel delivery pressure sensor signal voltage below normal for eight seconds. The ECM logs the code and sets the fuel pressure reading to a gauge pressure of zero, treating the data as invalid.
Will code 944 cause a loss of engine power?
Caterpillar's documentation states there are no performance effects from this code, since the ECM substitutes a default value for the fuel pressure reading. The engine should keep running normally, but the underlying wiring or sensor issue still needs attention.
What is SPN 94 FMI 4?
SPN 94 refers to the fuel delivery pressure parameter, and FMI 4 indicates the signal voltage is below the normal expected range, consistent with a short to ground or an open or damaged circuit.
What usually causes code 944 on CAT engines?
Common causes are damaged or corroded connectors and wiring, problems within the harness, out-of-place seals, intermittent electrical faults, a faulty fuel pressure sensor, or in some cases a faulty ECM.
Which CAT engines can show fault code 944?
This code applies to the C10, C11, C12, C13, C15, C16, C27, and C32 engine families.
How do I fix CAT code 944?
Start by inspecting the connectors, seals, and wiring harness around the fuel delivery pressure sensor for damage or corrosion. If wiring and connectors are good, test or replace the sensor. If the problem persists after that, ECM replacement may be necessary.