P0199: Oil temperature sensor signal dropping in and out
Engine oil temperature sensor intermittent
Severity: Monitor
TroubleCodes.net says this code often brings no noticeable drivability problem, so it is usually a sensor-circuit fault rather than an urgent one.
It gets more serious if:
- Inspect soon: Inspect soon if the temperature gauge climbs, an oil or temperature warning shows, or the engine runs poorly alongside the light, because the listed symptoms include possible overheating and low oil indicators.
P0199 in short
P0199 means the engine computer sees an on-and-off fault in the engine oil temperature sensor circuit. Common causes are damaged wiring, poor connections or a failing sensor. It often causes no obvious drivability problem, but check the temperature gauge and oil level.
The computer feeds the oil temperature sensor 5 volts and reads the voltage back. P0199 is set when that signal drops out or jumps now and then.
TroubleCodes.net lists damaged wiring, poor connections, a defective sensor, bent or corroded pins, open circuits and a thermostat fault. A fault of the reference voltage in the computer is listed as uncommon.
The Delaware DMV generic code list gives the same title, engine oil temperature sensor intermittent.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Damaged wiring or poor connections
Common general cause- Why it ranks here
- TroubleCodes.net lists wiring damage and poor connections first.
- What would change this
- Rises if wiggling the harness changes the reading. Falls if wiring tests clean.
Cause 2: Failing oil temperature sensor
Common general cause- Why it ranks here
- TroubleCodes.net lists a defective sensor.
- What would change this
- Rises if the sensor reading jumps when the wiring is steady. Falls if the signal is stable.
Cause 3: Bent, broken or corroded connector pins
Common general cause- Why it ranks here
- TroubleCodes.net names bent or broken pins and corrosion.
- What would change this
- Rises if pins look damaged. Falls if the connector is clean.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Inspect the oil temperature sensor connector and wiring for damaged pins, corrosion or chafing.
IfDamaged pins or wiring are found
It meansA connection fault is likely.
IfEverything looks fine
It meansTest the circuit.
Step 2: Have the sensor circuit checked for steady 5-volt reference, sensor output against the temperature chart, and continuity to the computer and ground.
Warning:Back-probing live connectors can short a circuit and damage the computer. Let a shop do it.
IfSignal drops out when the harness is moved
It meansWiring fault.
IfGood wiring but a wrong or unstable reading
It meansSensor fault.
Symptoms
- Check engine light
- Often no noticeable drivability problem
- Possible temperature or low oil level warning Gets more serious: stop and have it checked.
How to fix
Step 1: With the engine off and cool, check the oil temperature sensor connector and wiring for corrosion, bent pins or damage.
Step 2: Have the sensor circuit tested against the manufacturer's voltage or resistance chart before replacing the sensor.
Parts and cost context
- Engine control module (ECM / PCM):The engine computer is a rare cause. Confirm with circuit tests first. Labour varies; get a quote.
Labor varies by vehicle and shop; get a quote before you approve a repair.
Compare used part prices on PartPriceGuideOn your vehicle
We don't have reviewed vehicle-specific evidence for P0199 yet. The causes and tests above apply across vehicles.
Related codes
Sources and review
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error