OBD-II Code
P0198
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$80–$480
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0198 is the opposite of P0197 — the engine oil temperature sensor voltage rose above the calibrated high threshold, typically above 4.8 volts on a 0-5V circuit, which the ECU interprets as an open in the signal wire or a sensor that has failed open internally.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0198 is the opposite of P0197 — the engine oil temperature sensor voltage rose above the calibrated high threshold, typically above 4.8 volts on a 0…
P0198 is the opposite of P0197 — the engine oil temperature sensor voltage rose above the calibrated high threshold, typically above 4.8 volts on a 0-5V circuit, which the ECU interprets as an open in the signal wire or a sensor that has failed open internally. An open-circuit EOT sensor reads as if the oil were extremely cold (-40°F or pegged at the minimum scale value) because with no thermistor in the circuit, the signal voltage floats up to the 5V reference.
Cheapest first
- scan EOT live data with the engine fully warmed up — a reading pinned at -40°F or 'sensor open' after 20 minutes of operation is the dead giveaway.
- Disconnect the sensor at its connector and jumper the signal pin to ground at the harness side; the scanner should immediately swing to 300°F+ (reading the short you just created).
- If it does, the harness is intact and the sensor itself is open — swap it.
- If the scanner still reads -40°F with the signal grounded at the connector, the open is in the harness between the connector and the ECM; back-probe the signal and reference wires at both ends and check for continuity.
- Verify the 5V reference voltage at the sensor connector with KOEO — a missing reference points to ECM-side circuit damage or a blown internal regulator.
- The expensive misdiagnosis: replacing the EOT sensor when the actual fault was a corroded connector that became open after a winter of road-salt exposure; clean the connector before parts-throwing.
Vehicle-specific patterns2011-2019 Ford 6.7L Power Stroke routinely throws P0198 from EOT sensor open-circuit failure, often after coolant or oil intrusion at the connector s…
- 2011-2019Ford 6.7L Power Stroke routinely throws P0198 from EOT sensor open-circuit failure, often after coolant or oil intrusion at the connector seal — the sensor is the most common failure point in the engine's temperature-sensor stack.
- 2010-2017BMW N20 / N55 / S55 inline-6 sees P0198 from oil-filter-housing-related EOT failure; when the OFHG fails, the sensor connector floods with oil and the contacts oxidize until the circuit opens.
- 2007-2018RAM Cummins 6.7L sets P0198 from EOT sensor failure or harness break — the sensor's location near the oil cooler exposes it to constant heat cycling.
- 2008-2015Subaru FA20DIT turbo throws P0198 from the integrated oil-temp/pressure switch failing open; common at 80k-120k miles.
Estimated repair$80 to $480.
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