P0197 code meaning
Engine Oil Temperature Sensor A Circuit Low
Powertrain system Generic code P01xx codes Check engine light
What P0197 means
The engine oil temperature sensor A is an NTC thermistor fed with 5 V through a resistor: the hotter the oil, the lower the signal voltage. The engine module uses the oil temperature for variable cam timing (Ford disables it with cold oil or a sensor fault), engine protection and the oil life monitor; many engines have no such sensor and use a calculated oil temperature instead. P0197 means the signal voltage is below its lower limit, so the module would read implausibly hot oil (around 145–150 °C) – practically always a signal wire shorted to ground or an internally shorted sensor. Ford sets it below 0.16–0.20 V for 5 s; GM below 25 Ω in 20 of 50 samples – without a warning light on the 2018 LT4, with two trips on the 2019 version, so MIL behaviour depends on the manufacturer and model year. A substitute value is used.
P0197 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyEasy, DIY possible
- Typical labor0.3 to 1.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0197
- Check engine light on (depending on manufacturer)
- Oil temperature display at maximum or oil temperature warning
- Fan running constantly or power reduction possible
- Restricted cam timing (Ford)
Common causes of P0197
- Most likelySignal wire chafed against ground or the engine block
- PossibleSensor shorted internally
- PossibleOil or water in the connector (leakage current)
- Less likelyControl module input faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Engine oil temperature sensorSensor wiring
What each part of P0197 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 97 | The exact fault in that area. |
What to do next
- Note P0197 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0197
What does P0197 mean?
P0197 means "Engine Oil Temperature Sensor A Circuit Low". The engine oil temperature sensor A is an NTC thermistor fed with 5 V through a resistor: the hotter the oil, the lower the signal voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P0197?
Drive gently and only to a workshop. With P0197 the car can go into limp mode (reduced power) to protect itself.
Will P0197 fail an emissions test?
Yes, it can. P0197 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0197 to fix?
Difficulty: easy. A typical repair takes 0.3 to 1.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P0197 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.