P0199 Diagnostic Trouble Code: Engine Oil Temperature (EOT) Sensor Circuit Intermittent

Fault code P0199 is called “Engine Oil Temperature (EOT) Sensor Circuit Intermittent” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P0199

OBD-II fault code P0199 is a generic fault code defined as “intermittent signal in engine oil temperature sensor circuit”. It is set when the powertrain control module (PCM) detects an intermittent signal from the engine oil temperature sensor.

P0199 Diagnostic Trouble Code: Engine Oil Temperature (EOT) Sensor Circuit Intermittent

The engine oil temperature sensor (EOT) generates a signal that is used by the powertrain control module (PCM) to calculate fuel quality. It also calculates the injection timing and glow plug operation.

The EOT signal is also compared with signals from other sensors, such as the intake air temperature (IAT) and engine coolant temperature (ECT).

The EOT sensors receive a reference voltage from the PCM, which is typically 5 volts. The internal resistance changes with engine oil temperature and the voltage signal is sent back to the PCM.

EOT sensors are a type of negative temperature coefficient (NTC) thermistor. This means that the internal resistance is inversely proportional to the oil temperature. The EOT sensor signal voltage decreases when the engine oil temperature rises, and vice versa.

Code P0199 is set when the PCM detects an intermittent signal in the engine oil temperature sensor circuit. This usually indicates a short circuit or other circuit problem.

Symptoms of vehicle malfunctions

The main signal that an error P0199 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be written in the memory as a malfunction).
  2. Possible overheating due to coolant problems.
  3. Low oil level or oil sludge in the engine.
  4. Poor heating of interior in very cold weather.
  5. There may be no symptoms other than a stored fault code.

Error P0199 related to oil temperature is considered serious, so it is recommended to eliminate this problem as soon as possible. For example, if the oil temperature is too high, it may cause the engine to overheat.

Factors that can cause this error code

The error code P0199 can mean that one or more of the following problems have occurred:

  • Engine oil temperature sensor is defective.
  • Excessive resistance in oil temperature sensor circuit.
  • Damaged, burned, shorted, or corroded wiring.
  • Use of unsuitable engine oil.
  • Poor maintenance, such as irregular oil and oil filter changes.
  • Excessive mechanical wear and tear on the engine.
  • Mechanical failure of internal engine components.
  • Sometimes the cause is a faulty PCM module.

How to fix or reset OBD-2 code P0199

Some suggested steps for troubleshooting and fix the error code P0199:

  1. Read all data and stored error codes, using an OBD-II scanner.
  2. Clear the codes and check if error code P0199 appears again.
  3. Check the level and condition of the engine oil. If necessary, replace the oil along with the filter.
  4. Inspect the engine oil temperature sensor and associated wiring.
  5. Check the sensor with a digital multimeter, and replace it if necessary.
  6. Pay attention to mechanical wear on the engine. Physically check the oil temperature with a non-contact thermometer.

Diagnose and repair of problems

Check that the oil level is at the proper level, that it is not diluted with fuel or coolant, and that it is not of a thick, tarry consistency. If necessary, refill or replace the oil before proceeding with further diagnosis.

Perform a thorough visual inspection of the wiring to look for damaged, burned, disconnected, shorted, or corroded wires and connectors. If necessary, repair, clear the P0199 code and re-scan the system to see if the code returns.

Check the wiring with a multimeter

After no visible damage is found, check the resistance, ground and reference voltage. Compare all readings with those in the manual. If necessary, replace the wiring to ensure that all readings meet the manufacturer’s specifications.

Remember to disconnect the wiring from the PCM while checking resistance and continuity to prevent damage to the controller. The engine oil temperature sensor itself should also be checked, as it is part of the control circuit.

Checking the engine oil temperature sensor

Disconnect the engine oil temperature sensor connector, then measure the resistance between the two sensor terminals using a digital multimeter set to ohms. Start the engine and watch the meter readings, the values should decrease smoothly as the engine warms up.

If the engine temperature increases and the EOT resistance does not decrease, then the sensor is defective and must be replaced. In this case, replacement of the engine oil temperature sensor will solve the problem of error P0199.

On which vehicles does this problem occur most frequently

Fault code P0199 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Audi (A4)
  • Chevrolet (Cruze)
  • Dodge
  • Ford
  • GMC
  • Hyundai
  • Jeep
  • Land Rover
  • Nissan
  • Peugeot
  • Porsche (Cayenne)
  • Volkswagen

Fault code P0199 can sometimes be found with other errors. The most common are the following: P0195, P0196, P0197, P0198.


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