Code
B1220
ALFA ROMEO
B — Body
Fuel tank pressure sensor short to positive
Views:
UK: 5
EN: 13
RU: 6
AI status
Completed
Completed
100%
Causes
- Damaged/frayed wiring harness where the signal wire contacts a 12V source
- Corroded or pushed-back connector pin contacting positive terminal
- Failed fuel tank pressure sensor with internal short to battery positive
- Aftermarket equipment or repairs that routed 12V near the sensor wire
- PCM input driver fault (less common)
- Water/contamination in connector creating conductive path to positive
Symptoms
- Malfunction Indicator Lamp (MIL) lit or stored B1220 code
- Erratic or fixed high fuel tank pressure sensor reading on scan tool
- Possible EVAP system fault messages or failed emissions readiness
- Occasional rough idle or drivability issues if ECM limits functions
- Fuel odor if EVAP purge/venting is affected (less common)
What to check
- Read and record freeze-frame and live data for fuel tank pressure sensor with scan tool
- Visually inspect sensor connector and harness from tank to body/ECM for damage, pin corrosion, or contact with power wires
- Backprobe sensor connector: measure signal wire voltage with key ON (no crank)
- Check reference voltage (typically ~5V) and ground at the sensor connector
- Disconnect the sensor and see if code clears or if signal voltage changes
- Perform continuity check between signal wire and battery positive with harness disconnected (ignition OFF)
Signal parameters
- Reference supply: typically ~5.0 V (ECM reference) at sensor connector
- Signal output expected: approx. 0.5–4.5 V varying with pressure (vehicle-specific)
- Short-to-positive condition: signal reading close to battery voltage (~11–14 V) or stuck near reference max
- Ground: 0 V at sensor ground pin
- Continuity: signal wire to battery + should be open (no continuity) with ignition OFF
Diagnostic algorithm
- Connect a capable scan tool. Retrieve and note freeze-frame, pending codes, and live fuel tank pressure sensor values.
- Visually inspect the sensor connector and wiring along the route to the PCM for damage, pin corrosion, or contact with power circuits. Repair obvious damage.
- With ignition ON (engine OFF), backprobe the connector: verify reference voltage (~5V), ground, and signal voltage. If signal is near battery voltage, suspect short to positive.
- Disconnect the sensor. Re-check signal wire voltage at harness end. If high voltage remains, perform continuity test between the signal wire and battery positive (ignition OFF). Presence of continuity indicates a short in the harness.
- If no continuity to battery positive, bench-test or temporarily install a known-good sensor. If problem disappears, replace the sensor.
- If harness short confirmed, isolate sections of wiring (disconnect connectors along the route) to find where the signal wire contacts positive. Repair or replace damaged wire or connector as needed; use proper insulation and routing.
- After repairs, clear codes, perform relearn or EVAP system tests per manufacturer procedure, and verify system returns to normal on the scan tool and no reoccurrence of B1220.
- If wiring and sensor test good and problem persists, suspect PCM input driver fault and confirm with manufacturer-level diagnostics before replacing PCM.
Likely causes
- Chafed signal wire contacting a constant or switched 12V feed along the harness
- Bent/corroded connector pin touching the positive terminal in the connector
- Sensor internal short causing signal output to rise to battery voltage
- Recent body/fuel-sender service or wiring repair that introduced incorrect routing or pin connection
Fault status
Status
Fuel tank pressure sensor circuit short to positive voltage detected — signal higher than expected (possible wiring short to battery positive or sensor failure).
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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Code
B1220
FIAT
B — Body
Fuel tank pressure sensor short to positive
Views:
UK: 2
EN: 13
RU: 4
AI status
Completed
Completed
100%
Causes
- Damaged/frayed wiring harness where the signal wire contacts a 12V source
- Corroded or pushed-back connector pin contacting positive terminal
- Failed fuel tank pressure sensor with internal short to battery positive
- Aftermarket equipment or repairs that routed 12V near the sensor wire
- PCM input driver fault (less common)
- Water/contamination in connector creating conductive path to positive
Symptoms
- Malfunction Indicator Lamp (MIL) lit or stored B1220 code
- Erratic or fixed high fuel tank pressure sensor reading on scan tool
- Possible EVAP system fault messages or failed emissions readiness
- Occasional rough idle or drivability issues if ECM limits functions
- Fuel odor if EVAP purge/venting is affected (less common)
What to check
- Read and record freeze-frame and live data for fuel tank pressure sensor with scan tool
- Visually inspect sensor connector and harness from tank to body/ECM for damage, pin corrosion, or contact with power wires
- Backprobe sensor connector: measure signal wire voltage with key ON (no crank)
- Check reference voltage (typically ~5V) and ground at the sensor connector
- Disconnect the sensor and see if code clears or if signal voltage changes
- Perform continuity check between signal wire and battery positive with harness disconnected (ignition OFF)
Signal parameters
- Reference supply: typically ~5.0 V (ECM reference) at sensor connector
- Signal output expected: approx. 0.5–4.5 V varying with pressure (vehicle-specific)
- Short-to-positive condition: signal reading close to battery voltage (~11–14 V) or stuck near reference max
- Ground: 0 V at sensor ground pin
- Continuity: signal wire to battery + should be open (no continuity) with ignition OFF
Diagnostic algorithm
- Connect a capable scan tool. Retrieve and note freeze-frame, pending codes, and live fuel tank pressure sensor values.
- Visually inspect the sensor connector and wiring along the route to the PCM for damage, pin corrosion, or contact with power circuits. Repair obvious damage.
- With ignition ON (engine OFF), backprobe the connector: verify reference voltage (~5V), ground, and signal voltage. If signal is near battery voltage, suspect short to positive.
- Disconnect the sensor. Re-check signal wire voltage at harness end. If high voltage remains, perform continuity test between the signal wire and battery positive (ignition OFF). Presence of continuity indicates a short in the harness.
- If no continuity to battery positive, bench-test or temporarily install a known-good sensor. If problem disappears, replace the sensor.
- If harness short confirmed, isolate sections of wiring (disconnect connectors along the route) to find where the signal wire contacts positive. Repair or replace damaged wire or connector as needed; use proper insulation and routing.
- After repairs, clear codes, perform relearn or EVAP system tests per manufacturer procedure, and verify system returns to normal on the scan tool and no reoccurrence of B1220.
- If wiring and sensor test good and problem persists, suspect PCM input driver fault and confirm with manufacturer-level diagnostics before replacing PCM.
Likely causes
- Chafed signal wire contacting a constant or switched 12V feed along the harness
- Bent/corroded connector pin touching the positive terminal in the connector
- Sensor internal short causing signal output to rise to battery voltage
- Recent body/fuel-sender service or wiring repair that introduced incorrect routing or pin connection
Fault status
Status
Fuel tank pressure sensor circuit short to positive voltage detected — signal higher than expected (possible wiring short to battery positive or sensor failure).
Repair difficulty: Medium
Diagnostic time: 1-2 hours
Similar codes
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Was this AI description helpful?
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0
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0
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Code
B1220
Other
B — Body
Fuel Tank Pressure Sensor Circuit Open
Views:
UK: 22
EN: 56
RU: 28
AI status
Completed
Completed
100%
Causes
- Damaged/frayed wiring harness where the signal wire contacts a 12V source
- Corroded or pushed-back connector pin contacting positive terminal
- Failed fuel tank pressure sensor with internal short to battery positive
- Aftermarket equipment or repairs that routed 12V near the sensor wire
- PCM input driver fault (less common)
- Water/contamination in connector creating conductive path to positive
Symptoms
- Malfunction Indicator Lamp (MIL) lit or stored B1220 code
- Erratic or fixed high fuel tank pressure sensor reading on scan tool
- Possible EVAP system fault messages or failed emissions readiness
- Occasional rough idle or drivability issues if ECM limits functions
- Fuel odor if EVAP purge/venting is affected (less common)
What to check
- Read and record freeze-frame and live data for fuel tank pressure sensor with scan tool
- Visually inspect sensor connector and harness from tank to body/ECM for damage, pin corrosion, or contact with power wires
- Backprobe sensor connector: measure signal wire voltage with key ON (no crank)
- Check reference voltage (typically ~5V) and ground at the sensor connector
- Disconnect the sensor and see if code clears or if signal voltage changes
- Perform continuity check between signal wire and battery positive with harness disconnected (ignition OFF)
Signal parameters
- Reference supply: typically ~5.0 V (ECM reference) at sensor connector
- Signal output expected: approx. 0.5–4.5 V varying with pressure (vehicle-specific)
- Short-to-positive condition: signal reading close to battery voltage (~11–14 V) or stuck near reference max
- Ground: 0 V at sensor ground pin
- Continuity: signal wire to battery + should be open (no continuity) with ignition OFF
Diagnostic algorithm
- Connect a capable scan tool. Retrieve and note freeze-frame, pending codes, and live fuel tank pressure sensor values.
- Visually inspect the sensor connector and wiring along the route to the PCM for damage, pin corrosion, or contact with power circuits. Repair obvious damage.
- With ignition ON (engine OFF), backprobe the connector: verify reference voltage (~5V), ground, and signal voltage. If signal is near battery voltage, suspect short to positive.
- Disconnect the sensor. Re-check signal wire voltage at harness end. If high voltage remains, perform continuity test between the signal wire and battery positive (ignition OFF). Presence of continuity indicates a short in the harness.
- If no continuity to battery positive, bench-test or temporarily install a known-good sensor. If problem disappears, replace the sensor.
- If harness short confirmed, isolate sections of wiring (disconnect connectors along the route) to find where the signal wire contacts positive. Repair or replace damaged wire or connector as needed; use proper insulation and routing.
- After repairs, clear codes, perform relearn or EVAP system tests per manufacturer procedure, and verify system returns to normal on the scan tool and no reoccurrence of B1220.
- If wiring and sensor test good and problem persists, suspect PCM input driver fault and confirm with manufacturer-level diagnostics before replacing PCM.
Likely causes
- Chafed signal wire contacting a constant or switched 12V feed along the harness
- Bent/corroded connector pin touching the positive terminal in the connector
- Sensor internal short causing signal output to rise to battery voltage
- Recent body/fuel-sender service or wiring repair that introduced incorrect routing or pin connection
Fault status
Status
Fuel tank pressure sensor circuit short to positive voltage detected — signal higher than expected (possible wiring short to battery positive or sensor failure).
Repair difficulty: Medium
Diagnostic time: 1-2 hours
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