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Home / DTC / P0198 — Engine Oil Temperature Sensor A Circuit High

P0198 — Engine Oil Temperature Sensor A Circuit High

Detailed page for trouble code P0198.

34,405codes
59brands
11,914generic
22,491specific
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Code

P0198

Generic P — Powertrain

Engine Oil Temperature Sensor A Circuit High

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty engine oil temperature sensor (thermistor)
  • Open circuit in sensor wiring
  • Short to battery voltage (B+) in wiring or connector
  • Corroded/loose sensor connector or terminals
  • Poor ground or high-resistance connection
  • Intermittent wiring damage (chafing, broken conductor)

Symptoms

  • Check Engine Light (MIL) on and DTC P0198 stored
  • Incorrect or no oil temperature readout on dash or scan tool
  • Engine may revert to default oil-temperature value for control strategy
  • Possible altered warm-up behavior (longer warm-up, altered fan/shifting)
  • Occasional drivability safeguards or limp behavior on some vehicles

What to check

  • Retrieve freeze frame and freeze-data using a scan tool
  • Check for additional related codes (coolant temp, other sensors)
  • View live oil temperature and sensor voltage data with scan tool
  • Visually inspect sensor, connector, and wiring for damage/corrosion
  • Back-probe connector to measure sensor circuit voltage and reference
  • Measure sensor resistance (with sensor disconnected) and compare to expected pattern vs temperature

Signal parameters

  • Typical sensor circuit uses a thermistor; expected voltage range ~0.1–4.5 V depending on temperature and design
  • A 'circuit high' fault usually occurs when measured voltage is at or near battery voltage (e.g., >4.5 V) or open-circuit condition
  • Resistance decreases as temperature rises (NTC type); expect several kilo-ohms at ambient and lower at high temperature (values vary by manufacturer)
  • Reference supply to sensor often 5 V or pull-up provided by PCM — verify manufacturer-specific reference voltages

Diagnostic algorithm

  1. Verify DTC and note freeze frame/conditions with a scan tool; record oil temperature and sensor voltage.
  2. Visually inspect the oil temperature sensor, connector, and wiring harness at the sensor for damage, corrosion, oil contamination, or loose terminals.
  3. With connector connected, back-probe the sensor signal and measure voltage at key operating temperatures (cold and warmed up). Compare to expected ranges from the scan tool.
  4. Disconnect sensor and measure its resistance at ambient; if possible, measure resistance while heating (immersion in warm oil or controlled heat) to confirm thermistor behavior (resistance should change with temperature).
  5. Check for short to B+: with ignition ON, measure voltage at the harness signal pin with sensor disconnected — a high (battery) voltage indicates a short to B+ or internal pull-up; verify reference voltage from PCM.
  6. Check continuity from sensor ground/reference to PCM ground and from signal pin to PCM input; repair any opens, shorts, or high-resistance connections.
  7. If wiring and sensor check good, swap with a known-good sensor (if available) or replace the oil temperature sensor and retest.
  8. If fault persists after sensor and wiring repairs, test or consult procedure for PCM input circuit; consider module diagnosis or replacement only after wiring and sensor are verified.

Likely causes

  • Failed oil temperature sensor (most common)
  • Disconnected/corroded connector at sensor
  • Wire broken or pinched between sensor and PCM
  • Wire shorted to battery feed or other hot circuit
  • Damaged terminals causing high resistance/erratic voltage

Fault status

⚠️ Status
Engine Oil Temperature Sensor A Circuit High — PCM detects a voltage higher than expected (or open circuit) on the oil temperature sensor input. Check sensor, connector, wiring for open or short to B+, and verify PCM input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
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Code

P0198

GWM P — Powertrain

- High Oil Temperature Sensor

Brand: GWM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty engine oil temperature sensor (thermistor)
  • Open circuit in sensor wiring
  • Short to battery voltage (B+) in wiring or connector
  • Corroded/loose sensor connector or terminals
  • Poor ground or high-resistance connection
  • Intermittent wiring damage (chafing, broken conductor)

Symptoms

  • Check Engine Light (MIL) on and DTC P0198 stored
  • Incorrect or no oil temperature readout on dash or scan tool
  • Engine may revert to default oil-temperature value for control strategy
  • Possible altered warm-up behavior (longer warm-up, altered fan/shifting)
  • Occasional drivability safeguards or limp behavior on some vehicles

What to check

  • Retrieve freeze frame and freeze-data using a scan tool
  • Check for additional related codes (coolant temp, other sensors)
  • View live oil temperature and sensor voltage data with scan tool
  • Visually inspect sensor, connector, and wiring for damage/corrosion
  • Back-probe connector to measure sensor circuit voltage and reference
  • Measure sensor resistance (with sensor disconnected) and compare to expected pattern vs temperature

Signal parameters

  • Typical sensor circuit uses a thermistor; expected voltage range ~0.1–4.5 V depending on temperature and design
  • A 'circuit high' fault usually occurs when measured voltage is at or near battery voltage (e.g., >4.5 V) or open-circuit condition
  • Resistance decreases as temperature rises (NTC type); expect several kilo-ohms at ambient and lower at high temperature (values vary by manufacturer)
  • Reference supply to sensor often 5 V or pull-up provided by PCM — verify manufacturer-specific reference voltages

Diagnostic algorithm

  1. Verify DTC and note freeze frame/conditions with a scan tool; record oil temperature and sensor voltage.
  2. Visually inspect the oil temperature sensor, connector, and wiring harness at the sensor for damage, corrosion, oil contamination, or loose terminals.
  3. With connector connected, back-probe the sensor signal and measure voltage at key operating temperatures (cold and warmed up). Compare to expected ranges from the scan tool.
  4. Disconnect sensor and measure its resistance at ambient; if possible, measure resistance while heating (immersion in warm oil or controlled heat) to confirm thermistor behavior (resistance should change with temperature).
  5. Check for short to B+: with ignition ON, measure voltage at the harness signal pin with sensor disconnected — a high (battery) voltage indicates a short to B+ or internal pull-up; verify reference voltage from PCM.
  6. Check continuity from sensor ground/reference to PCM ground and from signal pin to PCM input; repair any opens, shorts, or high-resistance connections.
  7. If wiring and sensor check good, swap with a known-good sensor (if available) or replace the oil temperature sensor and retest.
  8. If fault persists after sensor and wiring repairs, test or consult procedure for PCM input circuit; consider module diagnosis or replacement only after wiring and sensor are verified.

Likely causes

  • Failed oil temperature sensor (most common)
  • Disconnected/corroded connector at sensor
  • Wire broken or pinched between sensor and PCM
  • Wire shorted to battery feed or other hot circuit
  • Damaged terminals causing high resistance/erratic voltage

Fault status

⚠️ Status
Engine Oil Temperature Sensor A Circuit High — PCM detects a voltage higher than expected (or open circuit) on the oil temperature sensor input. Check sensor, connector, wiring for open or short to B+, and verify PCM input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
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Code

P0198

HUMMER P — Powertrain

Engine Oil Temperature Sensor High Voltage

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty engine oil temperature sensor (thermistor)
  • Open circuit in sensor wiring
  • Short to battery voltage (B+) in wiring or connector
  • Corroded/loose sensor connector or terminals
  • Poor ground or high-resistance connection
  • Intermittent wiring damage (chafing, broken conductor)

Symptoms

  • Check Engine Light (MIL) on and DTC P0198 stored
  • Incorrect or no oil temperature readout on dash or scan tool
  • Engine may revert to default oil-temperature value for control strategy
  • Possible altered warm-up behavior (longer warm-up, altered fan/shifting)
  • Occasional drivability safeguards or limp behavior on some vehicles

What to check

  • Retrieve freeze frame and freeze-data using a scan tool
  • Check for additional related codes (coolant temp, other sensors)
  • View live oil temperature and sensor voltage data with scan tool
  • Visually inspect sensor, connector, and wiring for damage/corrosion
  • Back-probe connector to measure sensor circuit voltage and reference
  • Measure sensor resistance (with sensor disconnected) and compare to expected pattern vs temperature

Signal parameters

  • Typical sensor circuit uses a thermistor; expected voltage range ~0.1–4.5 V depending on temperature and design
  • A 'circuit high' fault usually occurs when measured voltage is at or near battery voltage (e.g., >4.5 V) or open-circuit condition
  • Resistance decreases as temperature rises (NTC type); expect several kilo-ohms at ambient and lower at high temperature (values vary by manufacturer)
  • Reference supply to sensor often 5 V or pull-up provided by PCM — verify manufacturer-specific reference voltages

Diagnostic algorithm

  1. Verify DTC and note freeze frame/conditions with a scan tool; record oil temperature and sensor voltage.
  2. Visually inspect the oil temperature sensor, connector, and wiring harness at the sensor for damage, corrosion, oil contamination, or loose terminals.
  3. With connector connected, back-probe the sensor signal and measure voltage at key operating temperatures (cold and warmed up). Compare to expected ranges from the scan tool.
  4. Disconnect sensor and measure its resistance at ambient; if possible, measure resistance while heating (immersion in warm oil or controlled heat) to confirm thermistor behavior (resistance should change with temperature).
  5. Check for short to B+: with ignition ON, measure voltage at the harness signal pin with sensor disconnected — a high (battery) voltage indicates a short to B+ or internal pull-up; verify reference voltage from PCM.
  6. Check continuity from sensor ground/reference to PCM ground and from signal pin to PCM input; repair any opens, shorts, or high-resistance connections.
  7. If wiring and sensor check good, swap with a known-good sensor (if available) or replace the oil temperature sensor and retest.
  8. If fault persists after sensor and wiring repairs, test or consult procedure for PCM input circuit; consider module diagnosis or replacement only after wiring and sensor are verified.

Likely causes

  • Failed oil temperature sensor (most common)
  • Disconnected/corroded connector at sensor
  • Wire broken or pinched between sensor and PCM
  • Wire shorted to battery feed or other hot circuit
  • Damaged terminals causing high resistance/erratic voltage

Fault status

⚠️ Status
Engine Oil Temperature Sensor A Circuit High — PCM detects a voltage higher than expected (or open circuit) on the oil temperature sensor input. Check sensor, connector, wiring for open or short to B+, and verify PCM input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
Repair manuals

Manual library for HUMMER

138

Browse 138 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HUMMER

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Code

P0198

LAND ROVER P — Powertrain

high circuit engine oil temperature sensor

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Faulty engine oil temperature sensor (thermistor)
  • Open circuit in sensor wiring
  • Short to battery voltage (B+) in wiring or connector
  • Corroded/loose sensor connector or terminals
  • Poor ground or high-resistance connection
  • Intermittent wiring damage (chafing, broken conductor)

Symptoms

  • Check Engine Light (MIL) on and DTC P0198 stored
  • Incorrect or no oil temperature readout on dash or scan tool
  • Engine may revert to default oil-temperature value for control strategy
  • Possible altered warm-up behavior (longer warm-up, altered fan/shifting)
  • Occasional drivability safeguards or limp behavior on some vehicles

What to check

  • Retrieve freeze frame and freeze-data using a scan tool
  • Check for additional related codes (coolant temp, other sensors)
  • View live oil temperature and sensor voltage data with scan tool
  • Visually inspect sensor, connector, and wiring for damage/corrosion
  • Back-probe connector to measure sensor circuit voltage and reference
  • Measure sensor resistance (with sensor disconnected) and compare to expected pattern vs temperature

Signal parameters

  • Typical sensor circuit uses a thermistor; expected voltage range ~0.1–4.5 V depending on temperature and design
  • A 'circuit high' fault usually occurs when measured voltage is at or near battery voltage (e.g., >4.5 V) or open-circuit condition
  • Resistance decreases as temperature rises (NTC type); expect several kilo-ohms at ambient and lower at high temperature (values vary by manufacturer)
  • Reference supply to sensor often 5 V or pull-up provided by PCM — verify manufacturer-specific reference voltages

Diagnostic algorithm

  1. Verify DTC and note freeze frame/conditions with a scan tool; record oil temperature and sensor voltage.
  2. Visually inspect the oil temperature sensor, connector, and wiring harness at the sensor for damage, corrosion, oil contamination, or loose terminals.
  3. With connector connected, back-probe the sensor signal and measure voltage at key operating temperatures (cold and warmed up). Compare to expected ranges from the scan tool.
  4. Disconnect sensor and measure its resistance at ambient; if possible, measure resistance while heating (immersion in warm oil or controlled heat) to confirm thermistor behavior (resistance should change with temperature).
  5. Check for short to B+: with ignition ON, measure voltage at the harness signal pin with sensor disconnected — a high (battery) voltage indicates a short to B+ or internal pull-up; verify reference voltage from PCM.
  6. Check continuity from sensor ground/reference to PCM ground and from signal pin to PCM input; repair any opens, shorts, or high-resistance connections.
  7. If wiring and sensor check good, swap with a known-good sensor (if available) or replace the oil temperature sensor and retest.
  8. If fault persists after sensor and wiring repairs, test or consult procedure for PCM input circuit; consider module diagnosis or replacement only after wiring and sensor are verified.

Likely causes

  • Failed oil temperature sensor (most common)
  • Disconnected/corroded connector at sensor
  • Wire broken or pinched between sensor and PCM
  • Wire shorted to battery feed or other hot circuit
  • Damaged terminals causing high resistance/erratic voltage

Fault status

⚠️ Status
Engine Oil Temperature Sensor A Circuit High — PCM detects a voltage higher than expected (or open circuit) on the oil temperature sensor input. Check sensor, connector, wiring for open or short to B+, and verify PCM input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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