P0451 on 2014-2018 Mazda Mazda3 — Evaporative Emission System Pressure Sensor/Switch Range/Performance
1 vehicles · 1 makes · $80-$250 repair
Most Reported On
P0451 is an OBD-II diagnostic trouble code meaning “Evaporative Emission System Pressure Sensor/Switch Range/Performance.” This code means the PCM detected that the EVAP system pressure sensor (fuel tank pressure sensor) is producing readings that are erratic, noisy, or outside the expected range. This sensor monitors pressure and vacuum in the fuel/EVAP system to detect leaks and manage vapor flow. A range/performance fault undermines the system's ability to run leak tests, which is an emissions issue. It usually triggers only the check engine light without affecting how the car drives. This code is most commonly reported on 2014-2018 Mazda Mazda3, with repair costs ranging from $80 to $250.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0451, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
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A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
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BlueDriver Pro Bluetooth Scanner
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Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
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LAUNCH CRP123X OBD-II Scanner
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A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
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Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
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- Oil reset, EPB, BMS, TPMS, injector coding
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FAQ
What does P0451 mean?
P0451 stands for "Evaporative Emission System Pressure Sensor/Switch Range/Performance." This code means the PCM detected that the EVAP system pressure sensor (fuel tank pressure sensor) is producing readings that are erratic, noisy, or outside the expected range. This sensor monitors pressure and vacuum in the fuel/EVAP system to detect leaks and manage vapor flow. A range/performance fault undermines the system's ability to run leak tests, which is an emissions issue. It usually triggers only the check engine light without affecting how the car drives.
What are the most common causes of P0451?
The most common causes of P0451 are: Faulty fuel tank/EVAP pressure sensor, Loose or faulty gas cap causing abnormal pressure, Damaged wiring or connector at the sensor, Blocked, kinked, or leaking EVAP hoses, Sensor contamination or internal fault, Failing PCM (less common). The specific cause varies by vehicle.
How much does it cost to fix P0451?
Repair costs for P0451 range from $80 to $250, depending on the vehicle and root cause.
Which vehicles are affected by P0451?
Au7o has documented P0451 across 1 vehicle models from 1 manufacturers: Mazda.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.