Generic fault code
P0940 — Hydraulic oil temperature sensor, circuit: signal high
The control unit stores code P0940 when it detects this fault: “Hydraulic oil temperature sensor, circuit: signal high”.
Indicative severity: MediumEngine (mechanical, cooling and lubrication)
Reviewed by Daniel Morales, founder of Reprorace SL, on
What does code P0940 mean?
The engine's mechanics, timing (camshaft and crankshaft), cooling and lubrication. Many of these codes check that the engine is in time and at the right temperature.
- System
- P · Powertrain
- Area
- Engine (mechanical, cooling and lubrication) · Car system: Engine and lubrication
- Type
- Generic (SAE J2012 / ISO 15031-6): the same meaning on every make
- Indicative severity
- Medium. Diagnose soon: it may raise emissions or consumption, or trigger limp-home mode.
What usually causes code P0940?
- Short circuit to battery or another voltage
- Open circuit (broken wire or terminal)
- Loose or corroded connector, backed-out terminals
The most likely causes come first. Only a check on the car confirms which one is yours.
What are the symptoms of code P0940?
- Oil pressure or engine warning light on
- Metallic noises from the engine
- Odd oil pressure or temperature readings
These are the usual symptoms of this kind of fault: not all of them always appear, and sometimes you notice nothing.
Can I keep driving with code P0940?
With care, and not for long. You can take the car to a workshop, ideally without long trips or heavy loads, and without putting it off: fuel use or emissions may rise and the car may go into limp-home mode (less power). If the light flashes, a red warning light comes on, the temperature rises or you notice a loss of power, noises or smoke, stop as soon as it is safe.
This is guidance only: only someone who checks the car can say whether it is safe to drive.
An indicative description of the code's generic meaning. Each manufacturer may give it a different meaning, conditions or tests: always follow its service information and your workshop's advice.
What you can do yourself
For this kind of fault
If the red oil pressure light comes on, stop as soon as it is safe and switch the engine off. With the engine cold and the car on level ground, check the level with the dipstick or on the dashboard.
Read the code and keep the report: with an ECO-LITE in the OBD socket you see it on your phone or computer, with the data captured when the fault happened.
Look for anything obvious: a loose connector, a disconnected hose, a fuel cap not closed properly or a low fluid level. Do not take apart anything you do not know.
Clear the code only after writing it down or after the repair. Clearing turns the light off, but it also deletes the freeze-frame data and the readiness monitors used at the inspection.
Drive normally for a few days and read the codes again. If the code comes back, the fault is still there: book the workshop and bring the report.
Read your car's fault codes on your phone
With an ECO-LITE in the OBD socket you see the codes in your account, with the data captured when the fault happened, and your workshop can check them remotely, always with your permission.
Related codes
- P0937Hydraulic oil temperature sensor, circuit: malfunction
- P0938Hydraulic oil temperature sensor: range/performance
- P0939Hydraulic oil temperature sensor, circuit: signal low
- P0941Hydraulic oil temperature sensor, circuit: intermittent
- P250AEngine oil level sensor, circuit: malfunction
- P250BEngine oil level sensor, circuit: range/performance
In the glossary
Read more: Remote OBD diagnostics: what it is, how it works and what it can't do