P0199
Engine Oil Temperature Sensor A Circuit Intermittent/Erratic
Engine oil temperature sensing
Generic OBD-II
Low
What it means
P0199 means the signal from engine oil temperature sensor A is cutting out or jumping around erratically. It's almost always a wiring or connector problem rather than the sensor itself. The engine keeps running normally, but the ECM loses accurate oil-temperature data during the dropouts, which can affect functions like cooling-fan control and warm-up strategy.
Low
Can I keep driving? Safe to drive — this is an intermittent sensor-signal fault; the engine runs normally, though oil-temperature-based functions may occasionally be off until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on (often intermittently)
- Inaccurate or fluctuating oil-temperature readings
- Usually no noticeable drivability change
- Possible minor loss of fuel economy
Common causes
Most likely first
- Loose, corroded, or backed-out connector at the oil temperature sensorLikely
- Chafed or intermittently shorted wiring in the sensor circuitCommon
- Faulty engine oil temperature sensor ACommon
- Poor ground or intermittent open in the harnessLess often
- ECM/PCM fault (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data, then wiggle-test the sensor connector and harness while watching the live oil-temperature reading for dropouts.
- Inspect the connector for corrosion, spread terminals, or moisture and reseat it.
- Check the wiring for chafing or an intermittent short along its run.
- Test or replace the oil temperature sensor if its signal stays erratic.
- Clear the code and road-test to confirm the intermittent is gone.
FAQ
Quick answers
Is it safe to drive with P0199?+
Yes. The oil temperature reading is an input the ECM uses for functions like fan control and warm-up strategy; an intermittent signal has little effect on drivability. Still, repair it.
Can I just clear P0199?+
Because the fault is intermittent it will likely return. Find and fix the loose connection or wiring first.
Related codes
Often seen with P0199
Read & clear P0199 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX