CAT Engine 1753 Fault Code: Engine Oil Temperature open/short to +batt
Also called Engine Oil Temperature 1 - Voltage Above Normal, Engine Oil Temperature 1 : Voltage Above Normal, Engine Oil Temperature Open/Short to +Batt, Engine Oil Temperature Sensor : Voltage Above Normal, Engine Oil Temperature Sensor Voltage Above Normal, Engine Oil Temperature Sensor voltage above normal
Engine Oil Temperature open/short to +batt · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 1753 (SPN 175 / FMI 3, also shown as flash code 37) means the ECM has seen the engine oil temperature sensor signal above 4.9 volts (some references list 4.92 VDC) for at least eight seconds, after the ECM has been powered for at least two seconds or three seconds depending on the version. This points to an open circuit or short to +battery on the signal wire. The engine will keep running using a substitute oil temperature value, but the fault should be diagnosed the same shift.
Medium severity. The engine keeps running because the ECM substitutes a default oil temperature value, so this is not an immediate shutdown fault. But losing real oil temperature data can mask overheating conditions and some versions report hard starting, rough idle, and excessive white smoke, so it should not be ignored for long.
What does CAT Engine error code 1753 mean?
Fault code 1753 is Caterpillar's designation for SPN 175, FMI 3: Engine Oil Temperature Sensor voltage above the normal operating range, also called Open/Short to +Batt. The engine oil temperature sensor (middle) is a two-terminal sensor that does not get supply voltage from the ECM. Instead the ECM watches the voltage on the signal wire (terminal 1) against a shared sensor common line (terminal 2).
When that signal voltage climbs above the ECM's acceptable ceiling, the ECM decides the sensor reading can't be trusted. This usually happens because the signal wire has an open circuit or has shorted to a positive battery voltage source somewhere in the harness.
Because the ECM can't get a valid oil temperature reading, it substitutes a stand-in value. On Cat ET, the oil temperature status is shown as the same value as the engine coolant temperature. If the coolant sensor has also failed, the ECM falls back to a fixed value: 65 °C (149 °F) if the engine is running, or −10 °C (14 °F) if the engine is not running.
What triggers a CAT Engine 1753 code?
The ECM logs this code when it has been powered for at least two seconds (one version says three seconds) and then reads a signal voltage above 4.9 volts (also listed as 4.92 VDC) for at least eight seconds continuously.
Common causes of 1753
- Faulty, corroded, or damaged connectors or wiring at the engine oil temperature sensor or its harness connector
- A short circuit in the signal wire, most often a short to +battery voltage
- Seals out of place at the connector, allowing moisture or debris intrusion
- A problem in the engine harness itself, including chafed or pinched wiring
- An intermittent connection issue that only shows up under vibration or temperature change
- A faulty engine oil temperature sensor that needs replacement
- A faulty ECM, though this is listed last and should only be suspected after wiring and sensor are cleared
How to troubleshoot CAT Engine 1753: first checks
- Pull up the active code on a display module or Cat ET and confirm it is CID 175-FMI 03 / SPN 175-FMI 3 before doing further work
- Inspect the engine oil temperature sensor connector and the engine harness connector for corrosion, loose pins, or damaged seals
- Check the signal wire (terminal 1) for a short to +battery voltage and check continuity of the sensor common wire (terminal 2), since it is shared across all engine temperature sensors
- Wiggle-test the harness near the sensor and along its routing while watching for the code to reset, since intermittent wiring problems are common
- Compare the oil temperature reading on Cat ET against coolant temperature to confirm the ECM is substituting values as expected
- If wiring and connectors check out, test or swap the oil temperature sensor itself before considering ECM replacement
How the code clears
No separate clearing step is listed beyond fixing the wiring, connector, or sensor fault that triggered the code. Once the signal voltage returns to a normal range and stays there, the ECM should stop flagging the fault active; codes can typically be cleared with a display module or Cat ET after the repair is confirmed.
Affected models and serial ranges
1753 appears in our records across 5 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C13 | Serial range not listed in source records |
| C15 | 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 |
Frequently asked questions
What does CAT code 1753 mean?
It means the ECM has detected the engine oil temperature sensor signal voltage above 4.9 volts (or 4.92 VDC) for at least eight seconds, which it interprets as an open circuit or a short to +battery on the sensor signal wire.
Is it safe to keep driving or running the machine with code 1753 active?
The engine will continue to run because the ECM substitutes a default oil temperature value, using coolant temperature or a fixed fallback value. It's not an emergency shutdown fault, but you lose real oil temperature monitoring, so get it diagnosed within the shift, especially if you notice hard starting, rough idle, or excessive white smoke.
What is flash code 37 on a CAT engine?
Flash code 37 is the diagnostic lamp equivalent of CID 175-FMI 03 / SPN 175-FMI 3, the same engine oil temperature sensor voltage above normal fault covered here.
What value does the ECM use for oil temperature when this code is active?
The ECM sets engine oil temperature to match the engine coolant temperature reading. If the coolant sensor has also failed, it uses 65 °C (149 °F) when the engine is running or −10 °C (14 °F) when the engine is not running.
Which CAT engines can set code 1753?
This code applies to the C13, C15, C175, C18, and C27 engine platforms.
Can a bad connector really cause this code, or is it always the sensor?
Connectors and wiring are the most commonly listed causes, including corrosion, damaged seals, shorted signal wires, and harness problems. A faulty sensor or ECM is possible but should be checked only after wiring and connectors are ruled out.
Does this code affect other temperature sensors too?
The troubleshooting procedure is identical for the engine coolant temperature sensor, both engine oil temperature sensors (middle and end), and the intake manifold air temperature sensor, since they share the same sensor common wiring and two-terminal design.