P0195
PowertrainEngine Oil Temperature Sensor Malfunction
This is usually a small job, not a wallet-emptier. The oil temperature sensor has stopped giving the ECU a sensible reading, and the most common culprits are the sensor itself or its wiring rather than anything deep inside the engine. The ECU uses oil temperature to fine-tune fuelling and warm-up behaviour, so when the signal goes haywire it throws the warning light on and may fall back to a default value.
ⓘ Information only. This page provides general educational information about fault code P0195. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0195 mean?
P0195 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Engine Oil Temperature Sensor Malfunction.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on the dash, often the only thing you'll actually notice
- • Oil temperature gauge reading wrong or stuck cold even after a proper warm-up run
- • Fuel economy creeping up a few per cent because the ECU is guessing at oil temp
- • A bit of hesitation or stumble when warm, as the fuelling map gets the wrong info
- • Occasional drop into limp mode where power is pulled back to protect the engine
Possible causes
Causes commonly associated with P0195, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. The oil temperature sensor itself has failed internally or got contaminated, this is where I'd put my money first
- 2. Damaged or corroded wiring in the sensor circuit, common where the loom runs near hot or vibrating parts
- 3. Dirty or moisture-affected sensor connector, a quick unplug and inspect often tells the story
- 4. Old or contaminated oil affecting how the sensor reads, more likely on a car that's overdue a service
- 5. Cooling system trouble throwing up temperatures that don't add up, which the ECU then logs as a sensor fault
- 6. A fault inside the ECU's input circuit, rare and the last thing to suspect once everything else checks out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Read the codes properly and note anything stored alongside it, especially coolant temp or other oil system faults that point at a bigger picture
- 2. Get under the car and eyeball the sensor, its connector and the loom for corrosion, chafing or a connector full of muck
- 3. Watch live oil temperature data on a scan tool, then unplug the sensor and see if the reading drops to the bottom of the scale, which confirms the ECU sees the circuit
- 4. Measure the sensor's resistance cold with a multimeter, you're looking for something around 2,500 to 3,000 ohms at room temperature on most setups
- 5. Check you've got a reference voltage at the connector, usually about 5 volts coming from the ECU, no voltage means a wiring or ECU problem upstream
- 6. Test continuity and the earth between the sensor and the control module to rule out a broken wire before you go buying parts
Common questions about P0195
What am I likely to pay to sort this out? +
If it turns out to be a corroded connector or a chafed wire, an independent garage might charge you £40 to £80 to clean it up and repair the loom. A new oil temperature sensor fitted usually lands somewhere in the £100 to £200 range at an independent, depending how buried the sensor is and how long it takes to reach. A main dealer will typically be a fair bit more, often half again on labour. Where it gets pricier is awkward wiring repairs or ECU diagnostics, which can climb into the mid hundreds.
How do I work out whether it's the sensor or the wiring on my own car? +
Start with the cheap test. Unplug the connector and look inside it. Green crud, bent pins or water sitting in there points at a wiring or connection fault rather than the sensor. Next, with a scan tool watching live data, disconnect the sensor and see if the reading drops right off. If it does, the ECU is reading the circuit fine and the sensor is your suspect. Then measure the sensor resistance cold, roughly 2,500 to 3,000 ohms at room temperature is normal, way off that means the sensor is dead. If the sensor checks out but you've still got the code, the wiring and earth between it and the ECU are next on the list.
Can I just swap the sensor or clean it myself? +
If you can get to it, yes, swapping the sensor is a sensible home job. It's normally one electrical plug and a thread to undo, much like changing a coolant temp sensor. The catch is access. On a lot of cars it sits on the sump or tucked behind the oil filter housing, so you may need the car up on ramps and a bit of patience. Cleaning a corroded connector with electrical contact cleaner and a smear of dielectric grease is free and sometimes all it needs. The sensor element itself can't really be cleaned, so if it's faulty it gets replaced, not revived. This one turns up fairly often on diesel applications, where oil temperature feeds injection timing and glow plug control, so the heat and vibration around the sump take their toll.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →