CAT Engine 1744 Fault Code: Fuel Temperature short to ground
Also called Engine Fuel Temperature 1 : Voltage Below Normal, Fuel Temperature Sensor - Voltage Below Normal, Fuel Temperature Sensor : Voltage Below Normal, Fuel Temperature Sensor Voltage Below Normal, Fuel Temperature Sensor voltage below norma, Fuel Temperature Sensor: Voltage Below Normal, Fuel Temperature Sensor:Voltage Below Normal, Fuel Temperature Short to Ground
Fuel Temperature short to ground · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 1744 (SPN 174 / FMI 4) means the ECM sees fuel temperature sensor signal voltage below 0.2 VDC for one second while the ECM has been powered for at least three seconds. The ECM logs the code, flags fuel temperature as invalid, and substitutes a default value (either 30 °C (86 °F) or 40 °C (104 °F) depending on the diagnostic body). Expect low power until it's resolved.
Medium severity. This code doesn't stop the engine, but the ECM runs on a default fuel temperature value and derates power, so fuel-related performance and possibly fuel economy or emissions control can be affected until it's fixed. Diagnose it within the shift rather than ignoring it.
What does CAT Engine error code 1744 mean?
CAT fault code 1744 flags a problem with the Fuel Temperature Sensor circuit on C10 through C32 engines. The sensor tells the ECM how hot or cold the fuel is so it can fine-tune fuel delivery and injection timing. When the ECM can't trust that reading, it falls back to a fixed default temperature instead of the real one.
This specific code, FMI 4, means the signal voltage is reading too low, essentially looking like a short to ground or an open circuit rather than a valid sensor reading. The ECM catches this, logs the fault, and substitutes a default fuel temperature so the engine keeps running, just without accurate fuel temperature compensation.
Because the engine loses this feedback, you'll typically notice reduced power (the diagnostic text calls it 'low power') alongside the fault. It's not an emergency shutdown condition, but it does mean the engine isn't running at its intended calibration.
What triggers a CAT Engine 1744 code?
The ECM sets this code when it reads a sensor signal voltage below 0.2 VDC sustained for one second, and only after the ECM has already been powered for at least three seconds. The fuel temperature sensor normally receives a regulated 5.0 VDC supply from the ECM, and the ECM also runs an automatic calibration routine whenever it's powered with the engine off for at least five seconds.
Common causes of 1744
- Connectors, pins, or sockets at the sensor or harness that are not fully coupled or fully inserted
- Corrosion, abrasion, or pinch points in the wiring harness
- An open or short circuit in the sensor circuit
- A short between the signal wire and ground
- A short between the analog sensor common and the signal wire
- An open circuit in the 5-volt supply wire to the sensor
- A short between the 5-volt supply and the signal wire
- A faulty or degraded fuel temperature sensor that needs replacement
- A faulty ECM (less common, but listed as a possible cause)
- General harness problems or intermittent connection issues
How to troubleshoot CAT Engine 1744: first checks
- Visually inspect the fuel temperature sensor connector and ECM connector for pins that are not fully seated, corrosion, or physical damage
- Trace the harness between the sensor and ECM looking for chafe points, pinches, or abrasion damage, especially anywhere it runs near moving parts or sharp edges
- With a meter, check the signal wire (terminal 1 at the sensor connector) for a short to ground and check the sensor return/common wire (terminal 2) for shorts to the signal wire
- Verify the 5-volt supply wire to the sensor is intact and not open or shorted to the signal wire
- Test the sensor itself; if wiring checks out clean, swap or bench-test the sensor to rule it out
- Check for intermittent connections by wiggling the harness and connectors while monitoring the signal, since intermittent problems are a listed cause
How the code clears
No separate clearing step is listed beyond fixing the underlying wiring, connector, or sensor issue. Once the ECM reads a valid signal voltage back in the acceptable range, the fault should stop being active; confirm with a service tool that the code clears and does not re-log after a drive cycle.
Affected models and serial ranges
1744 appears in our records across 10 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 |
| C175 | Serial range not listed in source records |
| C18 | 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 code 1744 mean?
It means the ECM detected fuel temperature sensor signal voltage below 0.2 VDC for one second, indicating a short to ground, open circuit, or bad sensor/wiring. The ECM logs the fault and uses a default fuel temperature value instead of the real reading.
Will code 1744 shut down my engine?
No. The engine keeps running, but the ECM substitutes a default fuel temperature (30 °C / 86 °F or 40 °C / 104 °F depending on the ECM software) and you may notice reduced power, described in CAT's diagnostic text as 'low power.'
What's the most common cause of this fault?
Wiring and connector issues are the most frequently listed causes: loose or unseated connectors, corrosion, chafed wiring, or a short between the signal wire and ground. The sensor itself or the ECM can also be at fault, but wiring problems are checked first.
Which engines can trigger code 1744?
This code applies to CAT C10, C11, C12, C13, C15, C16, C175, C18, C27, and C32 engines that use the electronic fuel temperature sensor circuit.
Is code 1744 the same as a short to ground on the fuel temperature sensor?
It can be. One of the OEM descriptions specifically labels this code as 'Fuel Temperature Short to Ground,' since a shorted signal wire will pull the voltage below the 0.2 VDC threshold the ECM is watching for.
Do I need a scan tool to diagnose this code?
A scan tool or CAT service tool helps confirm the code is active and lets you monitor live sensor voltage, but basic checks with a multimeter on the sensor connector, signal wire, and 5-volt supply wire can identify most wiring-related causes without special equipment.
Can I keep operating the machine with code 1744 active?
The engine will typically keep running, but since fuel temperature is defaulted and power is reduced, it's best to diagnose and repair the fault within the shift rather than running it long-term, since the ECM is compensating with a substituted value instead of real data.