Wiring problems, such as a loose connector, corroded pins or chafed wires that lose contact now and then (both sources). Faulty engine oil temperature sensor (both sources). Engine cooling system problems, for example an engine that overheats or never warms up properly (OBD-Codes.com). PCM failure (both sources; check everything else first).

Repair a loose connector, corroded terminal or damaged wiring at the oil temperature sensor. Replace the engine oil temperature sensor. Fix the underlying cooling system problem if the engine overheats or doesn't warm up (OBD-Codes.com). Repair or replace the PCM only after the sensor, wiring and cooling system check out.

P0199🔧 Engine / engine oil temperature sensorStop and fix promptly

P0199: Engine Oil Temperature Sensor Intermittent (Meaning, Causes, Fixes)

Q: What does P0199 mean?

P0199 means the engine computer saw the engine oil temperature sensor's signal drop out or jump around now and then. Both OBD-Codes.com and RepairPal list a failed sensor, wiring problems and, rarely, the PCM; OBD-Codes.com also lists cooling system problems. Because the fault comes and goes, start with the connector and wiring, and confirm the engine warms up and holds a normal temperature. The engine oil temperature (EOT) sensor tells the engine computer (PCM) how hot the oil is. OBD-Codes.com says the PCM uses this signal for things like fuel quantity, injection timing and glow plug operation, and also compares it with the intake air and coolant temperature sensors as a cross-check. EOT sensors are most common on diesels, and OBD-Codes.com names Ford Powerstroke, Chevrolet/GMC Duramax, VW, Nissan, Dodge, Jeep and Audi among the vehicles that use one. The sensor is a thermistor that gets a 5-volt reference from the PCM; its resistance drops as the oil heats up, so the signal voltage goes down as the oil gets hotter. P0199 is the intermittent code: OBD-Codes.com says it sets when the PCM detects an intermittent problem with the sensor signal, and RepairPal says it sets when the PCM detects an incorrect signal from it. Unlike P0197 (circuit low) or P0198 (circuit high), which point to a steady fault, P0199 means the problem comes and goes. The sources differ slightly: OBD-Codes.com titles it 'Engine Oil Temperature Sensor Intermittent' and includes engine cooling system problems among the causes, while RepairPal titles it 'Circuit Intermittent/Erratic' and lists only the sensor, the PCM and wiring.

Q: Can I keep driving with P0199?

Stop and fix promptly. Check your temperature gauge before driving. RepairPal rates P0199 Urgent, and OBD-Codes.com calls it moderate to severe, warning that when it sets along with coolant temperature codes it can point to an engine that is overheating. If the gauge reads high, steam is coming from the engine, or you also have coolant temperature codes, pull over and shut the engine off rather than risk engine damage. If the engine warms up and runs at a normal temperature, an intermittent fault is more likely a loose connection, damaged wiring or a failing sensor, but both sources say to get it looked at soon.

Reviewed 2026-10-25 · Based on 2 cited source(s)

What P0199 means

The engine oil temperature (EOT) sensor tells the engine computer (PCM) how hot the oil is. OBD-Codes.com says the PCM uses this signal for things like fuel quantity, injection timing and glow plug operation, and also compares it with the intake air and coolant temperature sensors as a cross-check. EOT sensors are most common on diesels, and OBD-Codes.com names Ford Powerstroke, Chevrolet/GMC Duramax, VW, Nissan, Dodge, Jeep and Audi among the vehicles that use one. The sensor is a thermistor that gets a 5-volt reference from the PCM; its resistance drops as the oil heats up, so the signal voltage goes down as the oil gets hotter. P0199 is the intermittent code: OBD-Codes.com says it sets when the PCM detects an intermittent problem with the sensor signal, and RepairPal says it sets when the PCM detects an incorrect signal from it. Unlike P0197 (circuit low) or P0198 (circuit high), which point to a steady fault, P0199 means the problem comes and goes. The sources differ slightly: OBD-Codes.com titles it 'Engine Oil Temperature Sensor Intermittent' and includes engine cooling system problems among the causes, while RepairPal titles it 'Circuit Intermittent/Erratic' and lists only the sensor, the PCM and wiring.

Severity: can I keep driving?

Stop and fix promptly

Check your temperature gauge before driving. RepairPal rates P0199 Urgent, and OBD-Codes.com calls it moderate to severe, warning that when it sets along with coolant temperature codes it can point to an engine that is overheating. If the gauge reads high, steam is coming from the engine, or you also have coolant temperature codes, pull over and shut the engine off rather than risk engine damage. If the engine warms up and runs at a normal temperature, an intermittent fault is more likely a loose connection, damaged wiring or a failing sensor, but both sources say to get it looked at soon.

Common symptoms

Check engine light on (OBD-Codes.com; it is the only symptom listed)
If coolant temperature codes are set too, possible overheating (OBD-Codes.com)
RepairPal gives no symptom list for this code

Likely causes

Roughly most to least common, based on the sources below. Your vehicle may differ.

Wiring problems, such as a loose connector, corroded pins or chafed wires that lose contact now and then (both sources)
Faulty engine oil temperature sensor (both sources)
Engine cooling system problems, for example an engine that overheats or never warms up properly (OBD-Codes.com)
PCM failure (both sources; check everything else first)

Diagnostic steps you can do

⚠ Before you start

Work on a cool engine, parked on level ground with the parking brake set. Never work under a car supported only by a jack.

Visually inspect the oil temperature sensor and its wiring for loose connections or damaged wires, repair anything you find, clear the code and see if it comes back (OBD-Codes.com). With an intermittent code, gently wiggling the connector and harness while watching live data can help catch a loose spot.
Look up technical service bulletins (TSBs) for your year, make, model and engine (OBD-Codes.com).
Watch the dash temperature gauge. OBD-Codes.com says to confirm the engine reaches and holds normal operating temperature, and to fix any overheating or slow warm-up problem before testing the sensor. Check for coolant temperature codes too.
With a scan tool, watch the engine oil temperature reading. OBD-Codes.com's quick check: unplug the sensor and the reading should drop very low; jumper the two connector terminals and it should jump very high. If it does both, the wiring and PCM can see the input and the sensor is the likely problem.
With the sensor unplugged, measure resistance across its two terminals with a multimeter while the engine warms up. It should decrease smoothly; if the engine warms but resistance doesn't drop, OBD-Codes.com says to replace the sensor. Your service manual's resistance/temperature chart gives exact values.

Typical fixes

Repair a loose connector, corroded terminal or damaged wiring at the oil temperature sensor
Replace the engine oil temperature sensor
Fix the underlying cooling system problem if the engine overheats or doesn't warm up (OBD-Codes.com)
Repair or replace the PCM only after the sensor, wiring and cooling system check out

Repair costs vary widely by vehicle, region, parts brand and shop, so we don't quote prices. Get a written estimate after diagnosis.

🛠 When to call a pro

OBD-Codes.com's circuit checks: with the ignition on, look for a 5-volt reference at one sensor terminal. If it's missing, check continuity from the sensor reference pin to the PCM (an OL reading means an open circuit), and then whether 5 volts is leaving the PCM. No reference out of the PCM suggests a faulty PCM.
Check the ground side the same way, sensor ground to PCM ground, and then the PCM's own ground to chassis.
Use the manufacturer's diagnostic flow chart; OBD-Codes.com notes that testing varies by vehicle.

Where to buy

Plain search links. Always match parts to your exact year, make, model and engine.

OBD2 scanners on Amazon Parts at Advance Auto Parts catalog at RockAuto

FAQs

Is P0199 serious?

It can be. RepairPal rates it Urgent and OBD-Codes.com calls it moderate to severe, mainly because it can show up with an engine that is overheating. If your temperature gauge is normal and there are no coolant codes, it's more likely a loose connection or the sensor, but still get it fixed soon.

What's the difference between P0199 and P0197 or P0198?

They're the same sensor. P0197 and P0198 mean the circuit voltage is steadily too low or too high. P0199 means the signal is intermittent or erratic, so the fault comes and goes, which often points to a connector or wiring problem.

Is P0199 a Ford or Chevy code?

No, it's a generic OBD-II code. Google search suggestions for P0199 mention Ford, Chevy, Mercedes, Toyota, Jeep, Dodge and Honda, but neither source we used gives a brand-specific cause. Check for TSBs on your exact vehicle.

Will replacing the sensor fix P0199?

Sometimes, but not always. Both sources list wiring and the PCM, and OBD-Codes.com lists cooling system problems. Inspect the connector and wiring, and do the scan tool unplug-and-jumper check, before buying a sensor.

Sources

Last reviewed 2026-10-25. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.