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P0199 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.

Definition

P0199 is an OBD-II Code that means something is wrong with the engine oil temperature sensor circuit.

Meaning

A P0199 code is the result of the ECM (Engine Control Module) receiving a signal from the oil temperature sensor that is out-of-range. The engine oil temperature sensor is responsible for informing the ECM of how hot or cold the engine oil is. This condition sets a diagnostic trouble code (DTC) to keep the car from being damaged. Failsafe mode will stay on until the fault is resolved. 

Causes

This can be caused by any number of reasons, including but not limited to defective sensors, corroded connectors in or around the harness, faulty wiring in or around the harness, and many other things. 

Symptoms

Symptoms of P0199 can include any or all of the following: Engine Light will be illuminated; oil pressure light might also come on if there is low actual oil pressure; the vehicle may run roughly or stall under load (A/T); possibly reduced fuel economy.

Diagnosis

1. Perform a visual inspection of the oil temperature sensor and connector(s) in or around the harness for any signs of damage, corrosion, wiring issues, etc.

2. If no visible defects are found, perform an electrical test on the circuit/wiring while tapping into both ends to check that it is sending a signal that is within range.

3. Check that the ECM code matches this code precisely before replacing anything so you know what part to replace.

4. Replace defective parts if needed; otherwise proceed to fix any corroded connectors in or around the wiring harness with appropriate contact cleaner/lubricant and corrosion resistance tape (if necessary). 

5. Reset computer

Common mistakes

The following are common mistakes when diagnosing the trouble code P0199:

1. Confusing the cause of this code with another code that has a similar number of unrelated codes that have different numbers but are also accompanied by P0199.

2. Confusing the cause of this code with an actual fault in the engine oil temperature sensor itself (typically electrical).

3. Assuming it is fixed because there are no visible signs of damage to wiring, connectors, etc., or because all other components are working properly. The same system could still be sending faulty signals despite having no outward sign of trouble!

4. Forgetting to perform an electrical test on the circuit/wiring while tapping into both ends to check that it is sending a signal that is within range before replacing anything so you know what part to replace.

5. Forgetting to reset the computer after making repairs.

6. Replacing parts unnecessarily without first confirming that there is no other cause of the problem before beginning diagnostics or replacing components. 

7. Confusing P0199 with another trouble code having a similar number, such as P0100-P0199, P0420-P0429.

How serious is this?

A car with a P0199 trouble code is operating abnormally and can cause serious problems. In some cases, safe operation might be possible for a while, but it will eventually result in major damage or failure if left unresolved, especially overheating which may lead to serious engine damage.

What repairs can fix the code?

The following are solutions that may fix this problem:

1. Perform a visual inspection of the oil temperature sensor and connector(s) in or around the harness for any signs of damage, corrosion, wiring issues, etc.

2. If no visible defects are found, perform an electrical test on the circuit/wiring while tapping into both ends to check that it is sending a signal that is within range.

3. Check that the ECM code matches this code precisely before replacing anything so you know what part to replace. 

4. Replace defective sensor if needed; otherwise proceed to fix any corroded connectors in or around the wiring harness with appropriate contact cleaner/lubricant and corrosion resistance tape (if necessary). 

5. Reset and clear the code(s)

Related codes

Related P0199 codes: P0202, P0203, P0420, P0421, P0422, P0423, P0429, P0430

Related diagnostic trouble codes: DTC U0100-U0199, DTC C1212-C1214, DTC P0420-P0430, DTC P0121-P0125

How much does it cost to fix the P0199 code?

Repairs for this code typically cost between $100-$500. When diagnosing P0199 trouble codes, remember that the problem may not be the oil temperature sensor itself but rather corroded connectors in or around the wiring harness.

There are many possible causes of a P0199 DTC, including dirty oil, low coolant level, a faulty thermostat, or bad engine mounts. When performing inspections on your car to diagnose an intermittent concern like this one, always check all potential issues thoroughly before replacing any expensive parts.

Conclusion

In conclusion, the P0199 is a trouble code that indicates a problem with the oil temperature sensor. A car with this code should be taken to a mechanic as soon as possible to prevent serious damage from occurring. In some cases, it has been known for certain areas of the engine to warp and cause permanent issues if the problem goes left unresolved. 

The problems associated with this code can be caused by defects, poor electrical connections, faulty wiring, corroded connectors in or around the wiring harness, dirty oil due to not changing or inspecting it often enough, low coolant level which causes overheating if not fixed quickly because coolant is an essential part of keeping an engine cool especially one that runs at high speeds constantly like that on cars, a faulty thermostat, or bad engine mounts. 

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