P0198🔧 Engine oil temperature sensorStop and fix promptly

P0198: Engine Oil Temperature Sensor Circuit High (Meaning, Causes, Fixes)

Reviewed 2026-10-23 · Based on 2 cited source(s)

What P0198 means

The engine oil temperature (EOT) sensor tells the engine computer (PCM) how hot the engine oil is. OBD-Codes.com explains that the sensor gets a 5-volt reference from the PCM and changes its resistance with temperature: the hotter the oil, the lower the resistance and the lower the signal voltage. The PCM uses the reading for things like injection timing and glow plug operation and compares it with the intake air and coolant temperature sensors. OBD-Codes.com says P0198 sets when the PCM sees a high sensor signal, which usually indicates an open circuit, and that EOT sensors are often found on diesel engines (it names Ford Powerstroke, Chevrolet/GMC Duramax, VW, Nissan, Dodge, Jeep and Audi among vehicles that have one). RepairPal describes the trigger more loosely, saying the code sets when the PCM detects an incorrect signal from the sensor. The two sources word the name slightly differently: RepairPal uses 'Engine Oil Temperature Sensor Circuit High', while OBD-Codes.com uses 'Engine Oil Temperature Sensor High'. Related codes in the same family are P0195 (circuit), P0196 (range/performance), P0197 (circuit low) and P0199 (circuit intermittent/erratic). It is a generic code that can appear on any OBD-II vehicle with this sensor, though the exact test steps vary by make and model.

Severity: can I keep driving?

Stop and fix promptly

Check your temperature gauge before driving. RepairPal rates P0198 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 runs at a normal temperature, the fault is more likely the sensor or its wiring, but both sources say to get it looked at soon.

Common symptoms

Likely causes

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

  1. Faulty engine oil temperature sensor (OBD-Codes.com, RepairPal)
  2. Wiring problem, such as an open circuit, loose connection or damaged wire (OBD-Codes.com, RepairPal)
  3. Faulty engine computer (PCM), less common (OBD-Codes.com, RepairPal)
  4. Engine cooling system problems, such as an engine that overheats or doesn't warm up properly (OBD-Codes.com only)

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.

  1. Watch the temperature gauge. OBD-Codes.com says to confirm the engine reaches and holds normal operating temperature; if it overheats or never warms up, fix the cooling system first.
  2. Check whether coolant temperature codes are stored along with P0198, which OBD-Codes.com says points toward a cooling system problem.
  3. Inspect the oil temperature sensor connector and wiring for loose connections or damaged wires, repair anything you find, clear the code and see if it returns (OBD-Codes.com).
  4. Check for technical service bulletins (TSBs) for your vehicle (OBD-Codes.com).
  5. With a scan tool and multimeter, OBD-Codes.com describes testing the sensor's resistance as the engine warms (it should drop smoothly) and checking the 5-volt reference and ground circuits for an open. Use your service manual's resistance chart and wiring diagram, since values vary by vehicle.

Typical fixes

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

  • The temperature gauge reads high or the engine shows signs of overheating
  • Coolant temperature codes are set along with P0198
  • You don't have a multimeter or the service information for your engine's sensor values
  • The wiring checks point to the engine computer
  • The code returns after a new sensor

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

Can I drive with P0198?

Only if the engine is running at a normal temperature, and even then get it checked soon. RepairPal rates P0198 Urgent and OBD-Codes.com calls it moderate to severe. If the engine is overheating, stop driving.

What's the difference between P0197 and P0198?

Both are engine oil temperature sensor circuit codes. P0197 means the signal is too low, while P0198 means it's too high, which OBD-Codes.com says usually means an open circuit.

Does P0198 mean my oil is too hot?

Not necessarily. A high signal usually points to an open circuit in the sensor wiring rather than real oil temperature, but OBD-Codes.com says to rule out cooling system problems first, especially if coolant temperature codes are also set.

How much does it cost to fix P0198?

Neither source gives a repair cost for P0198. It can range from fixing a loose connector to replacing the sensor, so diagnose it first.

Sources

  1. OBD-Codes.com: P0198 Engine Oil Temperature Sensor High
  2. RepairPal: P0198 Engine Oil Temperature Sensor Circuit High (rated Urgent)

Last reviewed 2026-10-23. Code definitions and repair steps can vary by manufacturer. Confirm with your vehicle's service information.