P0195

Engine Oil Temperature Sensor Malfunction

P0195 is a generic OBD-II powertrain diagnostic trouble code: Engine Oil Temperature Sensor Malfunction. It is logged by the engine control unit when the fuel/inj monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P0195
Group
Powertrain
System
Fuel/Inj
Severity
Warning (MIL on)
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What P0195 means

P0195 is a generic OBD-II code set when the PCM detects that the Engine Oil Temperature (EOT) sensor is reporting a signal that is out of range, implausible, or inconsistent with other available temperature data. The EOT sensor is a negative temperature coefficient (NTC) thermistor — its resistance decreases as oil temperature rises — and the PCM converts the resulting voltage signal into a temperature reading used to adjust fuelling, ignition timing, cooling fan control, and oil change interval monitoring. When the signal voltage falls outside the expected window (typically 0.1–4.9 V) or disagrees significantly with coolant temperature at startup, the PCM stores P0195. The fault covers a broad range of electrical conditions including open circuits, short circuits, and sensor internal failures, making it a somewhat general code compared to dedicated high/low variants. Common causes include sensor degradation from prolonged exposure to hot, contaminated oil; corrosion in the sensor connector from condensation or oil seepage; and wiring damage from heat proximity. On vehicles where the EOT sensor is located in the oil pan or sump, physical damage from road debris is also possible. While this code rarely causes immediate driveability problems, it can mask a genuine oil overtemperature event or incorrectly suppress engine protection strategies, making timely diagnosis worthwhile.

Common causes

Most-frequently reported root causes when P0195 is logged.

  • 1
    Failed Engine Oil Temperature sensor (open or short circuit internally due to age or contamination)
  • 2
    Corroded or damaged sensor connector or wiring harness terminals
  • 3
    Oil contamination or sludge fouling the sensor element and skewing resistance
  • 4
    Physical damage to the sensor or its wiring (heat, road debris, or improper oil service)
  • 5
    Incorrect or non-OEM replacement sensor with wrong resistance characteristics
  • 6
    Loose sensor installation causing intermittent ground contact through the thread
  • 7
    PCM input circuit fault (rare — rule out sensor and wiring first)

Symptoms drivers notice

MIL (Check Engine Light) illuminated as the primary indicator
Oil temperature gauge reading abnormally (stuck at cold, pegged high, or erratic)
Incorrect oil life or oil change interval monitoring on vehicles with onboard oil-life systems
Possible minor fuelling or ignition timing deviations in cold-start conditions on vehicles using EOT for warm-up enrichment
No obvious driveability symptoms in many cases — fault is often a background electrical issue

How to diagnose P0195

A typical diagnostic flow when this code is present.

  1. 1
    Use an OBD-II scanner to confirm P0195 and check for additional codes — companion codes such as P0197/P0198 (oil temp low/high) help narrow whether the circuit is shorted or open
  2. 2
    Compare live EOT sensor data against coolant temperature at a cold start — both should read ambient temperature within a few degrees; a large discrepancy suggests a sensor or wiring fault
  3. 3
    Visually inspect the sensor, its connector, and the associated wiring for oil contamination, corrosion, heat damage, or physical impact
  4. 4
    With the ignition on (engine off), measure sensor signal voltage at the connector; a reading near 0 V suggests a short to ground, while a reading near 5 V suggests an open circuit
  5. 5
    Disconnect the sensor and measure its resistance at a known temperature — compare against the manufacturer's resistance-temperature curve (typically ~2.5 kΩ at 20 °C, ~300 Ω at 80 °C); out-of-spec resistance confirms sensor failure
  6. 6
    Check wiring continuity from the sensor connector to the PCM and verify the ground/return path has minimal resistance
  7. 7
    Replace the sensor if tests confirm failure, clear codes, and verify the live temperature reading tracks correctly through warm-up before closing the repair

Related powertrain codes

Frequently asked questions

Is it safe to drive with P0195?

Generally yes for short distances, as P0195 rarely causes immediate driveability issues. However, if the sensor is failing open (reporting falsely cold oil), the PCM may not activate oil-temperature-based protection strategies. Avoid high-load or track driving until the sensor is replaced.

Can contaminated engine oil trigger P0195?

Yes. Heavily contaminated or sludged oil can coat the sensor element and alter its thermal conductivity, causing it to report inaccurate temperatures. If the oil is overdue for a change, performing an oil service before condemning the sensor is a worthwhile first step.

Where is the Engine Oil Temperature sensor located?

Location varies by manufacturer. It is commonly found in the oil pan, the oil filter housing, or screwed into an oil gallery on the engine block. Some vehicles share the function with the oil pressure sensor in a combination sender unit. Consult vehicle-specific documentation to locate it before beginning diagnosis.

Does P0195 affect oil change interval reminders?

Yes, on vehicles that use an oil-life monitoring algorithm incorporating operating temperature. A failed EOT sensor may cause the system to calculate incorrect remaining oil life — either extending intervals unsafely or shortening them unnecessarily. Replacing the sensor restores accurate monitoring.

Disabling P0195 in software

RaceTune can permanently disable P0195 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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