Code
P0197
GWM
P — Powertrain
- Low oil temperature sensor
AI status
Completed
Completed
100%
Causes
- Faulty engine oil temperature sensor (thermistor)
- Open or short in sensor wiring (short to ground)
- Corroded or loose connector terminals at sensor or ECU
- Poor ground or missing reference voltage from ECU
- Incorrect oil level or severely low oil causing abnormal readings
- ECU input circuit fault or intermittent ECU connector issue
Symptoms
- Malfunction Indicator Lamp (MIL) or engine warning light illuminated
- Oil temperature gauge or cluster display reads abnormally low or not responding
- Engine control logic may run conservative (poor warm-up behavior) or set limp/derate conditions on some vehicles
- Stored freeze-frame data showing unusually low oil temperature reading
- Possible difficulty reaching normal operating temperature or incorrect oil-related diagnostics
What to check
- Read freeze-frame and current live data with a scan tool (compare oil temp to ambient and coolant temp)
- Verify freeze/continuous DTCs and whether code is current or intermittent
- Visually inspect sensor, connector and cable for damage, corrosion, bent pins or oil contamination
- Backprobe the sensor connector to measure signal voltage and reference voltage with ignition ON and engine running as appropriate
- Measure sensor resistance across terminals and compare to OEM chart (or heat/cool sensor to see resistance change)
- Check continuity and resistance between sensor connector and ECU harness connector; check for short to ground or to battery +
Signal parameters
- Sensor type: typically a temperature thermistor (resistance varies with temperature)
- Reference voltage: commonly a 5.0 V reference from ECU (verify OEM spec)
- Signal voltage range (typical): approx. 0.1–4.9 V depending on temperature and sensor design; consult OEM for exact values
- Open-circuit symptom: very high or absent voltage (no change with temperature)
- Short-to-ground symptom: signal ~0.0–0.2 V; short-to-battery: signal near reference voltage (≈5 V)
Diagnostic algorithm
- Connect a scan tool, read DTC P0197 and freeze-frame data. Note ambient temperature, engine runtime and related codes (coolant temp sensors, grounds).
- Visually inspect oil temperature sensor and harness for damage, oil intrusion, or loose pins. Repair any obvious connector issues before further testing.
- With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (typ. 5 V) and good ground. If reference or ground missing, trace to ECU/fuse/ground point.
- Measure sensor signal voltage with engine cold and then warm the sensor (carefully with a heat source or by running engine) and look for signal change on scan tool/voltmeter. No change suggests open or failed sensor.
- Remove sensor and measure its resistance with an ohmmeter and compare to OEM temperature vs resistance chart. If resistance does not change with temperature or is out of spec, replace sensor.
- If sensor tests good, perform harness continuity checks between sensor connector and ECU connector and check for short to ground/battery. Repair wiring faults as needed.
- If wiring and sensor are good but code persists, verify ECU input pin operation or consider ECU diagnostics/repair per manufacturer guidance.
- After repair or replacement, clear codes and perform verification drive or warm-up to confirm proper operation and that P0197 does not return.
Likely causes
- Damaged wiring harness or chafed insulation causing short to ground
- Corroded/loose sensor connector or pin pushed out
- Failed oil temperature sensor element (most common)
- Poor ECU ground or blown fuse affecting sensor circuit
Fault status
Status
P0197 — Engine oil temperature sensor circuit low input (low oil temperature sensor)
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
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