Code
P0199
GWM
P — Powertrain
- Oil temperature sensor fault
Views:
UK: 17
EN: 26
RU: 27
AI status
Completed
Completed
100%
Causes
- Open or short in oil temperature sensor wiring
- Corroded or loose sensor connector
- Failed oil temperature sensor (thermistor)
- Poor sensor ground or missing reference voltage
- Oil contamination or mechanical damage to sensor
- Faulty ECM (rare)
Symptoms
- Check engine MIL lamp illuminated
- Incorrect or no oil temperature reading on dash/instrument cluster
- Engine warm-up or fan control behaving abnormally
- Reduced fuel economy or altered engine calibration during warm-up (depending on control strategy)
- Stored fault code(s) related to oil temperature
What to check
- Read freeze frame and live data with a scan tool (oil temp PID, related PIDs)
- Visually inspect sensor connector and wiring for damage, oil, corrosion or loose pins
- Backprobe sensor connector and verify reference voltage and ground present with ignition on
- Wiggle test wiring while monitoring live data for intermittent changes
- Measure sensor resistance or voltage while monitoring temperature change (cold vs warm)
- Check for related codes that indicate power/ground or communication faults
Signal parameters
- Typical sensor output: voltage signal between approx. 0.5–4.5 V (varies by model). Voltage normally falls as oil temperature rises for NTC-type sensors.
- Reference circuit: switched 5 V or pull-up to ECU — verify presence of reference voltage at connector with ignition ON.
- Open-circuit: sensor voltage often reads near reference rail or no continuity; short-to-ground or low resistance will pull voltage near 0 V.
- Note: exact voltage/resistance values vary by vehicle — confirm specs in the GWM service manual.
Diagnostic algorithm
- Retrieve and record freeze-frame data and live oil temperature PID with a scan tool. Note if code is stored as Circuit High / Implausible.
- Visually inspect sensor, harness, and connector for oil contamination, corrosion, damage, or loose pins. Repair any obvious damage.
- With ignition ON (engine OFF), backprobe connector: verify reference voltage (usually 5 V or ECU pull-up) and a good ground. If missing, trace wiring to ECU/fuse/ground.
- Measure sensor output voltage at connector while warming engine (or by applying heat to sensor) and observe PID change. For NTC sensors voltage should change smoothly as temperature changes.
- If equipped with removable sensor, remove and measure sensor resistance at known temperatures and compare to specification. If readings are out of spec, replace sensor.
- Perform a wiggle/stress test on harness while monitoring live data to find intermittent opens/shorts.
- If wiring and sensor check good, inspect ECU grounds and related fuses. Repair/replace damaged wiring or connector as needed.
- After repairs, clear codes and verify normal operation by running the engine to operating temperature and confirming oil temp PID behavior and no return of the code.
- If fault persists after sensor and wiring checks, consider ECU diagnosis or reflashing per manufacturer procedures.
Likely causes
- Damaged wiring harness near sensor (chafing, pinched or melted)
- Connector pins corroded with oil ingress
- Sensor failed due to overheating or age
- Poor electrical ground at engine block or sensor mounting
- Aftermarket oil filter or adapter interfering with sensor
Fault status
Status
Engine control module detected abnormal oil temperature sensor circuit signal (high/implausible). Check sensor, connector, and wiring for open, short, or poor connection. Replace faulty component(s) and verify on-road.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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