Fault code P0198 – a step-by-step guide to diagnosing and fixing it

Error code P0198 is displayed and the check engine light is on - what does this mean?

DTC P0198 is recognized by the OBD system when there is a problem with the engine oil temperature sensor circuit. This EOBD fault code indicates that the voltage in the signal circuit of the engine oil temperature sensor is too high. The exact designation may vary for different manufacturers, but the basic error remains the same.

What causes can this error code have?

• Defective engine oil temperature sensor
• Damaged wiring to the oil temperature sensor
• Corroded or loose plug connections
• Short circuit in the sensor cable
• Defective engine control unit (ECU)
• Interrupted ground connection
• Dirty or oily plug

What symptoms occur in parallel with fault code P0198?

• Check engine light: The check engine light lights up continuously
• Incorrect temperature display: The oil temperature display shows unrealistic values
• Engine protection functions: The engine can switch to emergency running mode
• Starting problems: Extended starting times when the engine is cold
• Rough engine running: Particularly noticeable at low temperatures

How can the problem with error code P0198 be rectified?

• Repairing trouble code P0198 requires a systematic diagnosis of the oil temperature sensor circuit.
• Sensor replacement: Replace the defective engine oil temperature sensor with a new original part and reprogram the control unit
• Cable repair: Check and repair damaged wiring between sensor and control unit, including insulation and shielding
• Clean plug connection: Clean all plug connections with contact spray and ensure tight connections
• Check ground connection: Check and repair the ground connection of the sensor to the engine block
• Control unit diagnostics: Have the engine control unit checked for defects and replaced or reprogrammed if necessary