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Home / DTC / P0451 — EVAP System Pressure Sensor/Switch A Circuit Range/Performance

P0451 — EVAP System Pressure Sensor/Switch A Circuit Range/Performance

Detailed page for trouble code P0451.

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59brands
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22,491specific
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Code

P0451

Generic P — Powertrain

EVAP System Pressure Sensor/Switch A Circuit Range/Performance

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

Causes

  • Faulty EVAP pressure sensor or pressure switch
  • Open or short in the sensor/switch wiring or connector
  • Poor or corroded ground or reference voltage (ECM side)
  • Contaminated or clogged sensor port or tubing
  • Faulty purge/vent control (causing abnormal pressures)
  • Faulty PCM (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • EVAP system readiness monitor may fail (vehicle may not pass emissions test)
  • Possible fuel smell in rare cases if venting abnormal (not always present)
  • Usually no immediate drivability issues such as stalling or loss of power

What to check

  • Read and record freeze-frame and live-data related to EVAP pressure sensor values
  • Inspect sensor connector and wiring for damage, corrosion, or disconnected pins
  • Check for stored EVAP-related codes (P0450–P0453, P0440–P0457) and related modules’ data
  • Visually inspect EVAP hoses, canister, and fittings for cracks, kinks or blockages
  • Perform a smoke test of the EVAP system to find leaks or restrictions if applicable

Signal parameters

  • Typical EVAP pressure sensor: 0–5.0 V analog output (varies by pressure; mid-range ~2.5 V at ambient)
  • Pressure-switch type: open/closed circuit with reference to 0 V or 5 V signal depending on design
  • Expected steady sensor response to applied known pressure/vacuum — smooth change in voltage proportional to pressure
  • Reference voltage to sensor usually ~5 V (check vehicle spec)

Diagnostic algorithm

  1. Connect OBD-II scanner; confirm P0451 and note freeze-frame data and related codes
  2. Monitor live EVAP pressure sensor voltage and comparison to reported pressure while key ON and engine OFF and during engine running if applicable
  3. Perform a visual inspection of wiring and connector; repair any obvious damage and clear corrosion
  4. Backprobe sensor connector: check reference voltage (usually 5 V), check ground continuity, measure sensor signal while applying vacuum/pressure
  5. If sensor signal is erratic or out of range, detach sensor and measure resistance or bench-test per manufacturer spec; if pressure-switch type, check continuity changes with applied pressure
  6. Apply controlled vacuum/pressure to the EVAP port (hand vacuum pump or pressure source) and confirm sensor output changes smoothly and within expected range
  7. Perform wiggle test on harness while monitoring live data to detect intermittent faults
  8. If wiring and sensor test good, inspect EVAP lines, purge and vent valves for blockages that could cause abnormal pressure readings
  9. If all components and wiring test normal, consider ECM input circuit testing or ECM replacement per manufacturer procedures

Likely causes

  • Broken or pinched harness between sensor and ECM
  • Water/condensation or corrosion at the sensor connector
  • Sensor damaged by road/debris/contamination
  • Connector not fully seated or bent terminal
  • Blocked EVAP line or canister causing out-of-range reading

Fault status

⚠️ Status
PCM detected EVAP pressure sensor/switch circuit A output outside expected range or not responding correctly. MIL set — further inspection of sensor, wiring, EVAP components, and ECM input required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

P0451

GWM P — Powertrain

- Invalid indicator / uncontrolled fuel pressure sensor

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

Causes

  • Faulty EVAP pressure sensor or pressure switch
  • Open or short in the sensor/switch wiring or connector
  • Poor or corroded ground or reference voltage (ECM side)
  • Contaminated or clogged sensor port or tubing
  • Faulty purge/vent control (causing abnormal pressures)
  • Faulty PCM (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • EVAP system readiness monitor may fail (vehicle may not pass emissions test)
  • Possible fuel smell in rare cases if venting abnormal (not always present)
  • Usually no immediate drivability issues such as stalling or loss of power

What to check

  • Read and record freeze-frame and live-data related to EVAP pressure sensor values
  • Inspect sensor connector and wiring for damage, corrosion, or disconnected pins
  • Check for stored EVAP-related codes (P0450–P0453, P0440–P0457) and related modules’ data
  • Visually inspect EVAP hoses, canister, and fittings for cracks, kinks or blockages
  • Perform a smoke test of the EVAP system to find leaks or restrictions if applicable

Signal parameters

  • Typical EVAP pressure sensor: 0–5.0 V analog output (varies by pressure; mid-range ~2.5 V at ambient)
  • Pressure-switch type: open/closed circuit with reference to 0 V or 5 V signal depending on design
  • Expected steady sensor response to applied known pressure/vacuum — smooth change in voltage proportional to pressure
  • Reference voltage to sensor usually ~5 V (check vehicle spec)

Diagnostic algorithm

  1. Connect OBD-II scanner; confirm P0451 and note freeze-frame data and related codes
  2. Monitor live EVAP pressure sensor voltage and comparison to reported pressure while key ON and engine OFF and during engine running if applicable
  3. Perform a visual inspection of wiring and connector; repair any obvious damage and clear corrosion
  4. Backprobe sensor connector: check reference voltage (usually 5 V), check ground continuity, measure sensor signal while applying vacuum/pressure
  5. If sensor signal is erratic or out of range, detach sensor and measure resistance or bench-test per manufacturer spec; if pressure-switch type, check continuity changes with applied pressure
  6. Apply controlled vacuum/pressure to the EVAP port (hand vacuum pump or pressure source) and confirm sensor output changes smoothly and within expected range
  7. Perform wiggle test on harness while monitoring live data to detect intermittent faults
  8. If wiring and sensor test good, inspect EVAP lines, purge and vent valves for blockages that could cause abnormal pressure readings
  9. If all components and wiring test normal, consider ECM input circuit testing or ECM replacement per manufacturer procedures

Likely causes

  • Broken or pinched harness between sensor and ECM
  • Water/condensation or corrosion at the sensor connector
  • Sensor damaged by road/debris/contamination
  • Connector not fully seated or bent terminal
  • Blocked EVAP line or canister causing out-of-range reading

Fault status

⚠️ Status
PCM detected EVAP pressure sensor/switch circuit A output outside expected range or not responding correctly. MIL set — further inspection of sensor, wiring, EVAP components, and ECM input required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0450 P0452 P0453 P0440 P0442 P0446
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Code

P0451

HUMMER P — Powertrain

Evaporative Emission Control System Pressure Sensor Range/Performance

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

Causes

  • Faulty EVAP pressure sensor or pressure switch
  • Open or short in the sensor/switch wiring or connector
  • Poor or corroded ground or reference voltage (ECM side)
  • Contaminated or clogged sensor port or tubing
  • Faulty purge/vent control (causing abnormal pressures)
  • Faulty PCM (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • EVAP system readiness monitor may fail (vehicle may not pass emissions test)
  • Possible fuel smell in rare cases if venting abnormal (not always present)
  • Usually no immediate drivability issues such as stalling or loss of power

What to check

  • Read and record freeze-frame and live-data related to EVAP pressure sensor values
  • Inspect sensor connector and wiring for damage, corrosion, or disconnected pins
  • Check for stored EVAP-related codes (P0450–P0453, P0440–P0457) and related modules’ data
  • Visually inspect EVAP hoses, canister, and fittings for cracks, kinks or blockages
  • Perform a smoke test of the EVAP system to find leaks or restrictions if applicable

Signal parameters

  • Typical EVAP pressure sensor: 0–5.0 V analog output (varies by pressure; mid-range ~2.5 V at ambient)
  • Pressure-switch type: open/closed circuit with reference to 0 V or 5 V signal depending on design
  • Expected steady sensor response to applied known pressure/vacuum — smooth change in voltage proportional to pressure
  • Reference voltage to sensor usually ~5 V (check vehicle spec)

Diagnostic algorithm

  1. Connect OBD-II scanner; confirm P0451 and note freeze-frame data and related codes
  2. Monitor live EVAP pressure sensor voltage and comparison to reported pressure while key ON and engine OFF and during engine running if applicable
  3. Perform a visual inspection of wiring and connector; repair any obvious damage and clear corrosion
  4. Backprobe sensor connector: check reference voltage (usually 5 V), check ground continuity, measure sensor signal while applying vacuum/pressure
  5. If sensor signal is erratic or out of range, detach sensor and measure resistance or bench-test per manufacturer spec; if pressure-switch type, check continuity changes with applied pressure
  6. Apply controlled vacuum/pressure to the EVAP port (hand vacuum pump or pressure source) and confirm sensor output changes smoothly and within expected range
  7. Perform wiggle test on harness while monitoring live data to detect intermittent faults
  8. If wiring and sensor test good, inspect EVAP lines, purge and vent valves for blockages that could cause abnormal pressure readings
  9. If all components and wiring test normal, consider ECM input circuit testing or ECM replacement per manufacturer procedures

Likely causes

  • Broken or pinched harness between sensor and ECM
  • Water/condensation or corrosion at the sensor connector
  • Sensor damaged by road/debris/contamination
  • Connector not fully seated or bent terminal
  • Blocked EVAP line or canister causing out-of-range reading

Fault status

⚠️ Status
PCM detected EVAP pressure sensor/switch circuit A output outside expected range or not responding correctly. MIL set — further inspection of sensor, wiring, EVAP components, and ECM input required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0450 P0452 P0453 P0440 P0442 P0446
Repair manuals

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Code

P0451

LAND ROVER P — Powertrain

Rationality of the tank pressure sensor fuel

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

Causes

  • Faulty EVAP pressure sensor or pressure switch
  • Open or short in the sensor/switch wiring or connector
  • Poor or corroded ground or reference voltage (ECM side)
  • Contaminated or clogged sensor port or tubing
  • Faulty purge/vent control (causing abnormal pressures)
  • Faulty PCM (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • EVAP system readiness monitor may fail (vehicle may not pass emissions test)
  • Possible fuel smell in rare cases if venting abnormal (not always present)
  • Usually no immediate drivability issues such as stalling or loss of power

What to check

  • Read and record freeze-frame and live-data related to EVAP pressure sensor values
  • Inspect sensor connector and wiring for damage, corrosion, or disconnected pins
  • Check for stored EVAP-related codes (P0450–P0453, P0440–P0457) and related modules’ data
  • Visually inspect EVAP hoses, canister, and fittings for cracks, kinks or blockages
  • Perform a smoke test of the EVAP system to find leaks or restrictions if applicable

Signal parameters

  • Typical EVAP pressure sensor: 0–5.0 V analog output (varies by pressure; mid-range ~2.5 V at ambient)
  • Pressure-switch type: open/closed circuit with reference to 0 V or 5 V signal depending on design
  • Expected steady sensor response to applied known pressure/vacuum — smooth change in voltage proportional to pressure
  • Reference voltage to sensor usually ~5 V (check vehicle spec)

Diagnostic algorithm

  1. Connect OBD-II scanner; confirm P0451 and note freeze-frame data and related codes
  2. Monitor live EVAP pressure sensor voltage and comparison to reported pressure while key ON and engine OFF and during engine running if applicable
  3. Perform a visual inspection of wiring and connector; repair any obvious damage and clear corrosion
  4. Backprobe sensor connector: check reference voltage (usually 5 V), check ground continuity, measure sensor signal while applying vacuum/pressure
  5. If sensor signal is erratic or out of range, detach sensor and measure resistance or bench-test per manufacturer spec; if pressure-switch type, check continuity changes with applied pressure
  6. Apply controlled vacuum/pressure to the EVAP port (hand vacuum pump or pressure source) and confirm sensor output changes smoothly and within expected range
  7. Perform wiggle test on harness while monitoring live data to detect intermittent faults
  8. If wiring and sensor test good, inspect EVAP lines, purge and vent valves for blockages that could cause abnormal pressure readings
  9. If all components and wiring test normal, consider ECM input circuit testing or ECM replacement per manufacturer procedures

Likely causes

  • Broken or pinched harness between sensor and ECM
  • Water/condensation or corrosion at the sensor connector
  • Sensor damaged by road/debris/contamination
  • Connector not fully seated or bent terminal
  • Blocked EVAP line or canister causing out-of-range reading

Fault status

⚠️ Status
PCM detected EVAP pressure sensor/switch circuit A output outside expected range or not responding correctly. MIL set — further inspection of sensor, wiring, EVAP components, and ECM input required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0450 P0452 P0453 P0440 P0442 P0446
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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Code

P0451

MITSUBISHI P — Powertrain

EVAP.emission PRS.sensor range

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

Causes

  • Faulty EVAP pressure sensor or pressure switch
  • Open or short in the sensor/switch wiring or connector
  • Poor or corroded ground or reference voltage (ECM side)
  • Contaminated or clogged sensor port or tubing
  • Faulty purge/vent control (causing abnormal pressures)
  • Faulty PCM (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • EVAP system readiness monitor may fail (vehicle may not pass emissions test)
  • Possible fuel smell in rare cases if venting abnormal (not always present)
  • Usually no immediate drivability issues such as stalling or loss of power

What to check

  • Read and record freeze-frame and live-data related to EVAP pressure sensor values
  • Inspect sensor connector and wiring for damage, corrosion, or disconnected pins
  • Check for stored EVAP-related codes (P0450–P0453, P0440–P0457) and related modules’ data
  • Visually inspect EVAP hoses, canister, and fittings for cracks, kinks or blockages
  • Perform a smoke test of the EVAP system to find leaks or restrictions if applicable

Signal parameters

  • Typical EVAP pressure sensor: 0–5.0 V analog output (varies by pressure; mid-range ~2.5 V at ambient)
  • Pressure-switch type: open/closed circuit with reference to 0 V or 5 V signal depending on design
  • Expected steady sensor response to applied known pressure/vacuum — smooth change in voltage proportional to pressure
  • Reference voltage to sensor usually ~5 V (check vehicle spec)

Diagnostic algorithm

  1. Connect OBD-II scanner; confirm P0451 and note freeze-frame data and related codes
  2. Monitor live EVAP pressure sensor voltage and comparison to reported pressure while key ON and engine OFF and during engine running if applicable
  3. Perform a visual inspection of wiring and connector; repair any obvious damage and clear corrosion
  4. Backprobe sensor connector: check reference voltage (usually 5 V), check ground continuity, measure sensor signal while applying vacuum/pressure
  5. If sensor signal is erratic or out of range, detach sensor and measure resistance or bench-test per manufacturer spec; if pressure-switch type, check continuity changes with applied pressure
  6. Apply controlled vacuum/pressure to the EVAP port (hand vacuum pump or pressure source) and confirm sensor output changes smoothly and within expected range
  7. Perform wiggle test on harness while monitoring live data to detect intermittent faults
  8. If wiring and sensor test good, inspect EVAP lines, purge and vent valves for blockages that could cause abnormal pressure readings
  9. If all components and wiring test normal, consider ECM input circuit testing or ECM replacement per manufacturer procedures

Likely causes

  • Broken or pinched harness between sensor and ECM
  • Water/condensation or corrosion at the sensor connector
  • Sensor damaged by road/debris/contamination
  • Connector not fully seated or bent terminal
  • Blocked EVAP line or canister causing out-of-range reading

Fault status

⚠️ Status
PCM detected EVAP pressure sensor/switch circuit A output outside expected range or not responding correctly. MIL set — further inspection of sensor, wiring, EVAP components, and ECM input required.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

P0450 P0452 P0453 P0440 P0442 P0446
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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