What causes fault code P0195?

• Most likely: Faulty Engine Oil Temperature (EOT) sensor (internal open or short circuit) • Likely: Wiring harness issues (chafing, corrosion in connectors) • Possible: Faulty oil cooler thermostat or blocked oil passage near the sensor • Rare: Internal Engine Control Unit (ECU) failure

Powertrain (Engine & Gearbox)Standard EOBD

P0195 - Engine Oil Temperature Sensor Malfunction

Q: What are the symptoms of fault code P0195?

• Check Engine Light (MIL) illumination • Inaccurate or erratic oil temperature gauge readings • Engine may enter Limp Home Mode (reduced power) • Oil life monitor/service interval calculation issues • Potential failure in emission-related diagnostic monitors

Q: How do you fix fault code P0195?

STEP 1: Visual inspection of the sensor and connector. Check for oil intrusion in the plug (wicking) or green corrosion on pins. STEP 2: Check reference voltage. With ignition ON, verify 5.0V at the sensor harness and a clean ground connection. STEP 3: Measure sensor resistance. Typically at 20°C (68°F), resistance should be ~2500 Ohms; at operating temp (90°C/194°F), resistance should drop to ~250 Ohms. STEP 4: Use a scan tool to monitor Live Data. Perform a 'cold soak' test where oil and coolant temperatures should be within 2-3 degrees of each other after sitting overnight. STEP 5: If wiring and reference signals are correct but the data is erratic or fixed, replace the EOT sensor.

Last updated:1 February 2026

Related:Engine Oil Temperature (EOT) Sensor, Engine Control Unit (ECU), Wiring Harness, Oil Cooler

System

Powertrain (Engine & Gearbox)

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Technical Description

P0195 is a generic powertrain code indicating that the Engine Control Unit (ECU) has detected an irrational signal from the Engine Oil Temperature (EOT) sensor circuit. The EOT sensor is typically an NTC thermistor where resistance decreases as temperature increases. The ECU provides a 5V reference and monitors the voltage drop across the sensor. If the voltage remains outside calibrated limits for a predetermined period, P0195 is stored. This input is critical for monitoring oil viscosity, fan control, fuel maps, and 'Limp Home' strategies to prevent thermal engine damage.

Possible Causes

Faulty Engine Oil Temperature (EOT) sensor (internal open or short circuit)

Wiring harness issues (chafing, corrosion in connectors)

Faulty oil cooler thermostat or blocked oil passage near the sensor

Internal Engine Control Unit (ECU) failure

Symptoms

Check Engine Light (MIL) illumination

Inaccurate or erratic oil temperature gauge readings

Engine may enter Limp Home Mode (reduced power)

Oil life monitor/service interval calculation issues

Potential failure in emission-related diagnostic monitors

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P0195 - Engine Oil Temperature Sensor Malfunction

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P0195 - Engine Oil Temperature Sensor Malfunction

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