What Does P0451 Mean?
The fuel tank pressure sensor is operating outside its expected range or performance parameters. The sensor is producing readings that change too quickly, too slowly, or are not within the expected range for current operating conditions. The EVAP system monitor will not pass, and the check engine light will be on. The driver typically notices no drivability symptoms.
Common Causes
35%
Degraded fuel tank pressure sensor providing erratic or out-of-range readings
20%
Loose or damaged gas cap not maintaining proper tank pressure
20%
EVAP system leak affecting pressure sensor correlation with purge commands
15%
Intermittent wiring or connector problem at the FTP sensor
10%
Fuel tank deformation or damage affecting internal pressure characteristics
Diagnostic Steps
1
Monitor the FTP sensor reading over time with the engine running and EVAP system operating. Look for erratic jumps, flat-lining, or readings that don't change when the purge valve is commanded.
2
Inspect the gas cap for damage, worn O-ring seal, or improper seating. Replace the gas cap if there is any doubt about its seal integrity, then clear codes and retest.
3
Perform a smoke test on the EVAP system to check for leaks in hoses, connections, and the charcoal canister that could affect tank pressure readings.
4
Disconnect and reconnect the FTP sensor connector, checking for corrosion, moisture, or loose terminals. Wiggle the connector while monitoring live data for signal dropouts.
5
Compare the FTP sensor voltage at rest (engine off, cap removed) to specifications. With the cap sealed and purge valve commanded, verify the sensor responds proportionally to vacuum changes.
Estimated Repair Cost
$80 - $350
Parts + labor, varies by vehicle and location
The fuel tank pressure sensor is operating outside its expected range or performance parameters. The sensor is producing readings that change too quickly, too slowly, or are not within the expected range for current operating conditions. The EVAP system monitor will not pass, and the check engine li...
The most common cause of P0451 (Evaporative Emission Control System Pressure Sensor Range/Performance) is: Degraded fuel tank pressure sensor providing erratic or out-of-range readings
Typical repair costs for P0451 range from $80 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. This code reflects an EVAP monitoring concern only. No drivability or safety issues are present. Repair when convenient for emissions compliance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0451 to identify the root cause.
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Quick Info
Category
Powertrain
System
EVAP / Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
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