P0451 on Honda
Evaporative Emission System Pressure Sensor/Switch Range/Performance
P0451 on Honda vehicles indicates evaporative emission system pressure sensor/switch range/performance. Au7o has documented this code across 1 Honda model — most commonly on Accord. 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. Typical repair costs on Honda range from $25 to $400, depending on the specific model and root cause.
Common Causes of P0451
- •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)
P0451 on Honda by Model
Honda Accord(1 issue)
- P0442 — Small EVAP Leak from Degraded Fuel Cap Seal or Failing Purge Valve2003-2017
On the Honda Accord, P0442 (small EVAP leak) is one of the most common check-engine triggers and almost always traces to one of three components in order of likelihood: the fuel cap, the engine-bay canister purge valve, or the under-car canister vent solenoid. The gas cap's rubber O-ring hardens, cracks, and stops sealing with age (aftermarket caps are a frequent repeat offender on this model). When the cap is good, the electric canister purge valve (which sticks or leaks internally) and the vent solenoid are the next suspects. A common Honda giveaway is a P1457 or P0451/P0456 stored alongside P0442, which points to the canister vent-side hardware rather than the cap. Because the leak is small, it is often intermittent and may set after refueling.
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View P0451 across all makes →Frequently Asked Questions
What does P0451 mean on Honda?▼
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. On Honda specifically, this code is documented across 1 model.
What causes P0451 on Honda vehicles?▼
Common causes on Honda: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0451 on a Honda?▼
Repair costs on Honda range from $25 to $400, depending on the specific model and root cause.
Which Honda models have P0451 documented?▼
Au7o has documented P0451 on 1 Honda model: Accord.