Code P0198 indicates the powertrain control module (PCM) has detected a high voltage signal from the engine oil temperature sensor circuit. This typically means the sensor is reading an implausibly low temperature (high resistance) or the circuit is open, causing the voltage to rise near the reference voltage level.
The sensor itself has failed internally, often developing an open circuit or high resistance that causes the signal voltage to read too high.
A broken wire, corroded terminal, or loose connection in the signal or ground circuit can create an open loop, driving the voltage to the reference level.
If the signal wire is shorted to a 5V or 12V source, the PCM will see a constant high voltage, mimicking an open sensor.
Corrosion, bent pins, or a loose connector at the sensor can cause intermittent high resistance or an open circuit.
An internal fault in the PCM's input circuitry can cause a false high reading, but this is extremely uncommon and should only be considered after all other possibilities are ruled out.
It means the engine oil temperature sensor is sending a voltage signal that is higher than expected, which usually indicates a very cold reading or an open circuit.
In most cases, yes, you can drive, but the engine may not run optimally because the PCM uses oil temperature for fuel and timing adjustments. It's best to diagnose and repair it soon to avoid potential drivability issues.
No, PCM failure is extremely rare for this code. The vast majority of cases are due to a faulty sensor, wiring problem, or poor connection. Replacing the PCM without thorough diagnosis is almost always a mistake.
The most common fix is replacing the engine oil temperature sensor. Other repairs include fixing damaged wiring, cleaning corroded connectors, or repairing a short to voltage.