Code
B1390
ALFA ROMEO
B — Body
Oil temperature sensor short to ground
Views:
UK: 2
EN: 4
RU: 3
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring harness causing conductor to contact chassis ground
- Corroded, bent or contaminated sensor connector pins
- Failed oil temperature sensor (internal short)
- Poor or missing ground at ECU or sensor harness splice
- Aftermarket equipment or recent repairs that disturbed wiring
- Control module (ECU) internal fault (less common)
Symptoms
- Malfunction Indicator Lamp (MIL) or warning light illuminated
- Oil temperature gauge may read erratically or low/zero
- Incorrect oil temperature-related behaviors (cold enrichment, fan control) depending on system
- Possible drivability issues if engine management uses oil temp input
- Stored diagnostic trouble code(s) and freeze-frame data
What to check
- Retrieve freeze-frame data and any additional stored codes; note when the code set
- Visual inspection of oil temperature sensor, connector and wiring for damage, corrosion or pin deformation
- Check continuity between sensor return/ground and chassis ground; verify proper ECU ground connections
- Measure sensor harness voltage with ignition ON (engine OFF) — backprobe signal and reference circuits
- Unplug sensor and measure resistance of the sensor across its terminals at known temperatures (compare to manufacturer chart)
- Check for short-to-ground on the signal wire (multimeter continuity to chassis ground should be open or very high resistance)
Signal parameters
- Sensor type: typically NTC thermistor (resistance decreases as temperature rises)
- Typical signal voltage range at ECU: ~0.5–4.5 V depending on temperature and vehicle design (confirm with Alfa Romeo specifications)
- Typical resistance at ambient temperatures: on the order of kilo-ohms at ~20–25°C (compare to manufacturer chart)
- Expected behavior: high resistance (higher voltage) at low temp, low resistance (lower voltage) at high temp
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note whether code is current, pending or historical.
- Perform a careful visual inspection of the oil temperature sensor, connector, and routing of the wiring harness for chafing, pin corrosion, melted insulation, or evidence of rodent damage.
- With ignition OFF, disconnect the oil temperature sensor. Inspect connector pins for corrosion or damage and clean if needed.
- Measure resistance of the sensor across its terminals at ambient temperature. If possible, compare resistance to manufacturer specification or compare to a known-good sensor.
- With ignition ON (engine OFF), backprobe the sensor harness: measure signal wire voltage and reference voltage. A signal near 0 V or short to ground indicates a shorted signal circuit.
- Check continuity between the signal wire and chassis ground. If continuity is present (very low resistance), trace wiring for the short and repair damaged sections.
- If wiring and connectors check good, swap in a known-good sensor or replace the sensor and re-test.
- If fault persists after sensor and wiring verified/repaired, inspect ECU connector and ground points. If suspect, consult manufacturer guidance for ECU testing or replacement.
- After repairs, clear codes, perform a road/run test to confirm the code does not return and oil temperature readings behave normally.
Likely causes
- Shorted sensor signal wire to chassis ground due to damaged insulation
- Corroded connector causing low-resistance path to ground
- Failed NTC oil temperature sensor with internal short
- Broken/loose ground connection at engine block or harness splice
Fault status
Status
Oil temperature sensor circuit short to ground detected — low/shorted signal circuit between oil temp sensor and control module.
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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Code
B1390
FIAT
B — Body
Oil temperature sensor short to ground
Views:
UK: 2
EN: 5
RU: 3
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring harness causing conductor to contact chassis ground
- Corroded, bent or contaminated sensor connector pins
- Failed oil temperature sensor (internal short)
- Poor or missing ground at ECU or sensor harness splice
- Aftermarket equipment or recent repairs that disturbed wiring
- Control module (ECU) internal fault (less common)
Symptoms
- Malfunction Indicator Lamp (MIL) or warning light illuminated
- Oil temperature gauge may read erratically or low/zero
- Incorrect oil temperature-related behaviors (cold enrichment, fan control) depending on system
- Possible drivability issues if engine management uses oil temp input
- Stored diagnostic trouble code(s) and freeze-frame data
What to check
- Retrieve freeze-frame data and any additional stored codes; note when the code set
- Visual inspection of oil temperature sensor, connector and wiring for damage, corrosion or pin deformation
- Check continuity between sensor return/ground and chassis ground; verify proper ECU ground connections
- Measure sensor harness voltage with ignition ON (engine OFF) — backprobe signal and reference circuits
- Unplug sensor and measure resistance of the sensor across its terminals at known temperatures (compare to manufacturer chart)
- Check for short-to-ground on the signal wire (multimeter continuity to chassis ground should be open or very high resistance)
Signal parameters
- Sensor type: typically NTC thermistor (resistance decreases as temperature rises)
- Typical signal voltage range at ECU: ~0.5–4.5 V depending on temperature and vehicle design (confirm with Alfa Romeo specifications)
- Typical resistance at ambient temperatures: on the order of kilo-ohms at ~20–25°C (compare to manufacturer chart)
- Expected behavior: high resistance (higher voltage) at low temp, low resistance (lower voltage) at high temp
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note whether code is current, pending or historical.
- Perform a careful visual inspection of the oil temperature sensor, connector, and routing of the wiring harness for chafing, pin corrosion, melted insulation, or evidence of rodent damage.
- With ignition OFF, disconnect the oil temperature sensor. Inspect connector pins for corrosion or damage and clean if needed.
- Measure resistance of the sensor across its terminals at ambient temperature. If possible, compare resistance to manufacturer specification or compare to a known-good sensor.
- With ignition ON (engine OFF), backprobe the sensor harness: measure signal wire voltage and reference voltage. A signal near 0 V or short to ground indicates a shorted signal circuit.
- Check continuity between the signal wire and chassis ground. If continuity is present (very low resistance), trace wiring for the short and repair damaged sections.
- If wiring and connectors check good, swap in a known-good sensor or replace the sensor and re-test.
- If fault persists after sensor and wiring verified/repaired, inspect ECU connector and ground points. If suspect, consult manufacturer guidance for ECU testing or replacement.
- After repairs, clear codes, perform a road/run test to confirm the code does not return and oil temperature readings behave normally.
Likely causes
- Shorted sensor signal wire to chassis ground due to damaged insulation
- Corroded connector causing low-resistance path to ground
- Failed NTC oil temperature sensor with internal short
- Broken/loose ground connection at engine block or harness splice
Fault status
Status
Oil temperature sensor circuit short to ground detected — low/shorted signal circuit between oil temp sensor and control module.
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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Code
B1390
HUMMER
B — Body
Device Voltage Reference Input Circuit Malfunction
Views:
UK: 4
EN: 10
RU: 6
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring harness causing conductor to contact chassis ground
- Corroded, bent or contaminated sensor connector pins
- Failed oil temperature sensor (internal short)
- Poor or missing ground at ECU or sensor harness splice
- Aftermarket equipment or recent repairs that disturbed wiring
- Control module (ECU) internal fault (less common)
Symptoms
- Malfunction Indicator Lamp (MIL) or warning light illuminated
- Oil temperature gauge may read erratically or low/zero
- Incorrect oil temperature-related behaviors (cold enrichment, fan control) depending on system
- Possible drivability issues if engine management uses oil temp input
- Stored diagnostic trouble code(s) and freeze-frame data
What to check
- Retrieve freeze-frame data and any additional stored codes; note when the code set
- Visual inspection of oil temperature sensor, connector and wiring for damage, corrosion or pin deformation
- Check continuity between sensor return/ground and chassis ground; verify proper ECU ground connections
- Measure sensor harness voltage with ignition ON (engine OFF) — backprobe signal and reference circuits
- Unplug sensor and measure resistance of the sensor across its terminals at known temperatures (compare to manufacturer chart)
- Check for short-to-ground on the signal wire (multimeter continuity to chassis ground should be open or very high resistance)
Signal parameters
- Sensor type: typically NTC thermistor (resistance decreases as temperature rises)
- Typical signal voltage range at ECU: ~0.5–4.5 V depending on temperature and vehicle design (confirm with Alfa Romeo specifications)
- Typical resistance at ambient temperatures: on the order of kilo-ohms at ~20–25°C (compare to manufacturer chart)
- Expected behavior: high resistance (higher voltage) at low temp, low resistance (lower voltage) at high temp
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note whether code is current, pending or historical.
- Perform a careful visual inspection of the oil temperature sensor, connector, and routing of the wiring harness for chafing, pin corrosion, melted insulation, or evidence of rodent damage.
- With ignition OFF, disconnect the oil temperature sensor. Inspect connector pins for corrosion or damage and clean if needed.
- Measure resistance of the sensor across its terminals at ambient temperature. If possible, compare resistance to manufacturer specification or compare to a known-good sensor.
- With ignition ON (engine OFF), backprobe the sensor harness: measure signal wire voltage and reference voltage. A signal near 0 V or short to ground indicates a shorted signal circuit.
- Check continuity between the signal wire and chassis ground. If continuity is present (very low resistance), trace wiring for the short and repair damaged sections.
- If wiring and connectors check good, swap in a known-good sensor or replace the sensor and re-test.
- If fault persists after sensor and wiring verified/repaired, inspect ECU connector and ground points. If suspect, consult manufacturer guidance for ECU testing or replacement.
- After repairs, clear codes, perform a road/run test to confirm the code does not return and oil temperature readings behave normally.
Likely causes
- Shorted sensor signal wire to chassis ground due to damaged insulation
- Corroded connector causing low-resistance path to ground
- Failed NTC oil temperature sensor with internal short
- Broken/loose ground connection at engine block or harness splice
Fault status
Status
Oil temperature sensor circuit short to ground detected — low/shorted signal circuit between oil temp sensor and control module.
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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Code
B1390
OPEL
B — Body
Comfort Closing Circuit Low Voltage
Views:
UK: 3
EN: 6
RU: 6
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring harness causing conductor to contact chassis ground
- Corroded, bent or contaminated sensor connector pins
- Failed oil temperature sensor (internal short)
- Poor or missing ground at ECU or sensor harness splice
- Aftermarket equipment or recent repairs that disturbed wiring
- Control module (ECU) internal fault (less common)
Symptoms
- Malfunction Indicator Lamp (MIL) or warning light illuminated
- Oil temperature gauge may read erratically or low/zero
- Incorrect oil temperature-related behaviors (cold enrichment, fan control) depending on system
- Possible drivability issues if engine management uses oil temp input
- Stored diagnostic trouble code(s) and freeze-frame data
What to check
- Retrieve freeze-frame data and any additional stored codes; note when the code set
- Visual inspection of oil temperature sensor, connector and wiring for damage, corrosion or pin deformation
- Check continuity between sensor return/ground and chassis ground; verify proper ECU ground connections
- Measure sensor harness voltage with ignition ON (engine OFF) — backprobe signal and reference circuits
- Unplug sensor and measure resistance of the sensor across its terminals at known temperatures (compare to manufacturer chart)
- Check for short-to-ground on the signal wire (multimeter continuity to chassis ground should be open or very high resistance)
Signal parameters
- Sensor type: typically NTC thermistor (resistance decreases as temperature rises)
- Typical signal voltage range at ECU: ~0.5–4.5 V depending on temperature and vehicle design (confirm with Alfa Romeo specifications)
- Typical resistance at ambient temperatures: on the order of kilo-ohms at ~20–25°C (compare to manufacturer chart)
- Expected behavior: high resistance (higher voltage) at low temp, low resistance (lower voltage) at high temp
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note whether code is current, pending or historical.
- Perform a careful visual inspection of the oil temperature sensor, connector, and routing of the wiring harness for chafing, pin corrosion, melted insulation, or evidence of rodent damage.
- With ignition OFF, disconnect the oil temperature sensor. Inspect connector pins for corrosion or damage and clean if needed.
- Measure resistance of the sensor across its terminals at ambient temperature. If possible, compare resistance to manufacturer specification or compare to a known-good sensor.
- With ignition ON (engine OFF), backprobe the sensor harness: measure signal wire voltage and reference voltage. A signal near 0 V or short to ground indicates a shorted signal circuit.
- Check continuity between the signal wire and chassis ground. If continuity is present (very low resistance), trace wiring for the short and repair damaged sections.
- If wiring and connectors check good, swap in a known-good sensor or replace the sensor and re-test.
- If fault persists after sensor and wiring verified/repaired, inspect ECU connector and ground points. If suspect, consult manufacturer guidance for ECU testing or replacement.
- After repairs, clear codes, perform a road/run test to confirm the code does not return and oil temperature readings behave normally.
Likely causes
- Shorted sensor signal wire to chassis ground due to damaged insulation
- Corroded connector causing low-resistance path to ground
- Failed NTC oil temperature sensor with internal short
- Broken/loose ground connection at engine block or harness splice
Fault status
Status
Oil temperature sensor circuit short to ground detected — low/shorted signal circuit between oil temp sensor and control module.
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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Code
B1390
Other
B — Body
Oil Temperature Sensor Circuit Short To Ground
Views:
UK: 13
EN: 29
RU: 21
AI status
Completed
Completed
100%
Causes
- Damaged or chafed wiring harness causing conductor to contact chassis ground
- Corroded, bent or contaminated sensor connector pins
- Failed oil temperature sensor (internal short)
- Poor or missing ground at ECU or sensor harness splice
- Aftermarket equipment or recent repairs that disturbed wiring
- Control module (ECU) internal fault (less common)
Symptoms
- Malfunction Indicator Lamp (MIL) or warning light illuminated
- Oil temperature gauge may read erratically or low/zero
- Incorrect oil temperature-related behaviors (cold enrichment, fan control) depending on system
- Possible drivability issues if engine management uses oil temp input
- Stored diagnostic trouble code(s) and freeze-frame data
What to check
- Retrieve freeze-frame data and any additional stored codes; note when the code set
- Visual inspection of oil temperature sensor, connector and wiring for damage, corrosion or pin deformation
- Check continuity between sensor return/ground and chassis ground; verify proper ECU ground connections
- Measure sensor harness voltage with ignition ON (engine OFF) — backprobe signal and reference circuits
- Unplug sensor and measure resistance of the sensor across its terminals at known temperatures (compare to manufacturer chart)
- Check for short-to-ground on the signal wire (multimeter continuity to chassis ground should be open or very high resistance)
Signal parameters
- Sensor type: typically NTC thermistor (resistance decreases as temperature rises)
- Typical signal voltage range at ECU: ~0.5–4.5 V depending on temperature and vehicle design (confirm with Alfa Romeo specifications)
- Typical resistance at ambient temperatures: on the order of kilo-ohms at ~20–25°C (compare to manufacturer chart)
- Expected behavior: high resistance (higher voltage) at low temp, low resistance (lower voltage) at high temp
Diagnostic algorithm
- Read and record all DTCs and freeze-frame data. Note whether code is current, pending or historical.
- Perform a careful visual inspection of the oil temperature sensor, connector, and routing of the wiring harness for chafing, pin corrosion, melted insulation, or evidence of rodent damage.
- With ignition OFF, disconnect the oil temperature sensor. Inspect connector pins for corrosion or damage and clean if needed.
- Measure resistance of the sensor across its terminals at ambient temperature. If possible, compare resistance to manufacturer specification or compare to a known-good sensor.
- With ignition ON (engine OFF), backprobe the sensor harness: measure signal wire voltage and reference voltage. A signal near 0 V or short to ground indicates a shorted signal circuit.
- Check continuity between the signal wire and chassis ground. If continuity is present (very low resistance), trace wiring for the short and repair damaged sections.
- If wiring and connectors check good, swap in a known-good sensor or replace the sensor and re-test.
- If fault persists after sensor and wiring verified/repaired, inspect ECU connector and ground points. If suspect, consult manufacturer guidance for ECU testing or replacement.
- After repairs, clear codes, perform a road/run test to confirm the code does not return and oil temperature readings behave normally.
Likely causes
- Shorted sensor signal wire to chassis ground due to damaged insulation
- Corroded connector causing low-resistance path to ground
- Failed NTC oil temperature sensor with internal short
- Broken/loose ground connection at engine block or harness splice
Fault status
Status
Oil temperature sensor circuit short to ground detected — low/shorted signal circuit between oil temp sensor and control module.
Repair difficulty: Medium
Diagnostic time: 1-2 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
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0
Send to email