Code
P0454
HUMMER
P — Powertrain
Evaporative Emission Control System Pressure Sensor Intermittent
AI status
Completed
Completed
100%
Causes
- Loose, corroded or damaged sensor electrical connector
- Broken, chafed, or intermittent wiring in the sensor circuit
- Faulty EVAP/fuel tank pressure sensor (intermittent internal failure)
- Water intrusion or contamination at the sensor or connector
- Poor sensor ground or reference voltage (5V) issue
- Intermittent PCM input circuit problem (less common)
Symptoms
- Malfunction Indicator Lamp (MIL/CHECK ENGINE) illuminated intermittently
- EVAP-related codes may appear alongside (other EVAP codes)
- No noticeable change in drivability for most cases
- Vehicle may intermittently fail emissions readiness or emissions test
What to check
- Read and record freeze frame and pending codes; note when code set
- Use a scan tool to monitor fuel tank/EVAP pressure PID for intermittent drops, jumps, or erratic values
- Visually inspect sensor and connector for corrosion, bent pins, damage, or moisture
- Wiggle harness and connector while observing live data to reproduce the intermittent
- Backprobe and measure reference (usually 5V), sensor output voltage, and ground with key on/engine running
- Check for Service Bulletins or known issues for the specific HUMMER model/year
Signal parameters
- Expected sensor output: usually a steady analog voltage that varies with tank pressure (typical factory range ~0.5–4.5 V depending on design) — consult vehicle specifications
- Reference voltage: stable 5 V supply from PCM to sensor connector
- Ground: solid chassis/PCM ground with low resistance
- Intermittent condition shows sudden voltage spikes, drops to open-circuit (no signal), or rapid erratic fluctuations
Diagnostic algorithm
- Retrieve freeze-frame data and history; clear codes and test drive to confirm intermittent reoccurrence.
- Visually inspect sensor, mounting, and connector for damage, moisture, or corrosion. Repair or clean as needed.
- With a scan tool, monitor the EVAP/fuel tank pressure PID while performing a wiggle test on the harness and connector to reproduce the fault.
- Backprobe the sensor connector: verify stable 5V reference, stable ground, and sensor output. Compare to factory values. Note any intermittent loss while performing wiggle test.
- If wiring or connector shows intermittent behavior, repair or replace the damaged section, then retest.
- If wiring and connector are good but signal is still intermittent, remove and bench-test or replace the pressure sensor with a known-good unit and retest.
- After repairs, clear codes and confirm through a full drive cycle and re-scan for no recurrence. If intermittent issues persist, check PCM input circuit and consider professional module testing.
- Document repairs and recheck readiness monitors if required for emissions testing.
Likely causes
- Loose connector or partial pin contact at tank pressure sensor
- Wiring harness chafe that moves under load or vibration
- Sensor internal intermittent failure (works sometimes, then drops out)
- Corroded pins from moisture exposure in connector
- Intermittent 5V reference loss or intermittent ground
Fault status
Status
P0454 — Evaporative Emission Control System Pressure Sensor Intermittent. Intermittent or unstable sensor signal detected; inspect sensor, connector, and wiring.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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Repair manuals
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