P0198 - OBD Trouble Code

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One may notice effect on the drivability of the car like loss of engine power and acceleration, increased fuel consumption and Check Engine Light on along with ECM failure. However, all these are likely to happen other than the Check Engine Light flashing on the dashboard and the OBD code P0198 being stored in the PCM.

PCM (Powertrain Control Module) takes help of the EOT sensor to calculate fuel quality, injection timing and glow plug operation and is also compared to other temperature sensors such as the intake air temperature (IAT) sensor and engine coolant temperature (ECT) sensor for diagnostic purposes. A reference voltage of usually 5 volts is received by the sensor from the PCM which then vary their internal resistance in relation to engine oil temperature to send a return voltage signal to the PCM. The EOT sensor signal voltage goes down when the engine oil temperature goes up and vice versa. Code P0198 is set when the PCM detects a high engine oil temperature sensor signal which usually indicates an open circuit.

What causes the problem of Engine Oil Temperature Sensor High?

• Faulty Engine Oil Temperature (EOT) sensor
• EOT sensor harness is open or shorted
• EOT sensor circuit poor electrical connection

1. Engine Oil Temperature Sensor - Faulty sensor will affect the PCM decision making and thus hamper the engine performance with regards to fuel delivery system, exhaust system and combustion process. Buy new EOT sensor from us today.
2. Engine Control Module - Although faulty ECM is very rare, but needs to be checked for damages and if it requires reprogramming or not to function properly.
3. Oil Temperature Gauge - Check if the temperature gauge is working properly and replace if not.
4. Diagnostic Tools - High grade diagnostic tools are required to treat OBD code P0198 and avoiding any misdiagnosis. Buy from us now!
5. Thermistor - Check for faulty thermistor and replace if necessary. Buy new parts from us now!
6. Powertrain Control Module - PCM issues directly affects the engine control and transmission control module. Thus, replace faulty components now.

Check Engine Light illumination is the major symptom indicating OBD code P0198 error. The EOT system can also detect other problems with the vehicle and if the circuits of the EOT system have any problem, it won’t be able to monitor the oil temperature correctly.

• Repairing damaged wiring supplying the short to power
• PCM repair and reprogramming
• Addressing the low engine oil temperature 

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• Always start with a visual inspection of system wiring harnesses and connectors. We focus on wirings and connectors that are routed near and on the sensors and circuit, as well as those that are routed near sharp edges like the ones found on exhaust shields.
• Use technical service bulletins (TSB) in your vehicle information source to resolve this error. If you find one that matches the symptoms and code/s presented by the vehicle in question, it will very likely aid you in your diagnosis. TSB listings are compiled from thousands of successful repairs.
• Retrieve all the data codes and freeze frame the data using the scanner. This information may be helpful if the P0198 proves to be intermittent so write it down for later. Now, clear the codes and see if the P0198 is reset.
• Start the engine, allow it to reach normal operating temperature, and then let it idle (with the transmission in neutral or park), if the code is reset. Use the scanner data stream to observe sensor input data.
• Connect the Digital Voltmeter Ohm Meter test leads to the sensor ground and signal wires in order to monitor live data from the EOT sensor.
• Also check the voltage of the sensor in question, as well as voltage and ground signals. To prevent control module damage, disconnect related controllers prior to testing system circuit resistance with the DVOM.

Common Mistakes When Diagnosing The P0198 Code

Most of the time the EOT sensor itself may be the cause of P0198, using the proper tools and following the complete diagnostic procedure without skipping any steps is required as to avoid unneeded repairs. Monitoring the sensor data from the scan tool live data stream is the only way to check for proper operation, and the sensor should not be replaced until it is tested. Also, always check for damaged wiring and connections as well as PCM faults.