P0455 on Ford vehicles
EVAP Large or Gross Leak Detected — what it means on a Ford, whether it's safe to drive, and the fixes by model and year.
P0455 on a Ford means evap large or gross leak detected. Most vehicles stay drivable short-term, but diagnose it promptly. The most common cause is missing, loose, or wrong-fit fuel cap (typically $0–$60). Pick your Ford model below for its known failure patterns, recalls, and TSBs.
What does P0455 mean on a Ford?
P0455 is set when the EVAP system's gross-leak monitor detects an opening approximately 0.090 inches (2.3 mm) or larger — or in many cases, no seal at all. This is the size of a missing gas cap, a disconnected hose, or a failed vent solenoid stuck open. The system cannot hold pressure or vacuum for the calibration period, so the ECM concludes a major leak.
P0455 is a standardized OBD-II code, so its definition is the same on every Ford. What differs by model and engine is which cause is most likely — pick your Ford model below for a diagnosis tuned to its known failure patterns, recalls, and TSBs.
Is it safe to drive a Ford with P0455?
In most cases a Ford stays drivable for short trips with P0455 active, but diagnose and repair it promptly. This is a low-severity code — ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.
What causes P0455 on a Ford?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Missing, loose, or wrong-fit fuel cap — Always check first. A locking gas cap from another vehicle that almost fits is a common source. | Most common | $0–$60 |
| Disconnected or split EVAP hose | Common | $30–$200 |
| EVAP vent valve stuck open (will not seal during the monitor test) | Common | $80–$350 |
| Damaged or rusted-through fuel filler neck | Occasional | $200–$700 |
| Cracked or broken EVAP charcoal canister | Occasional | $200–$600 |
| Damaged O-ring at the fuel pump assembly cover | Rare | $30–$500 |
| Rodent damage to EVAP hoses (parked vehicles) | Occasional | $30–$200 |
Repair costs are typical US ranges and vary by Ford model, model year, and labor rate. A diagnostic trouble code is a symptom, not a guaranteed failed part — confirm the root cause before replacing anything.
P0455 by Ford model
Select your Ford model and year for a P0455 diagnosis tuned to that vehicle's failure patterns, recalls, and TSBs.
Ford F-150
43 recalls on record across the years covered below.
Ford Escape
3,364 NHTSA owner complaints · 24 recalls on record across the years covered below.
Ford Explorer
2,694 NHTSA owner complaints · 43 recalls on record across the years covered below.
Ford Bronco
328 NHTSA owner complaints · 21 recalls on record across the years covered below.
Ford Mustang
771 NHTSA owner complaints · 22 recalls on record across the years covered below.
Complaint and recall counts are NHTSA totals for the model years covered on this site, not counts specific to P0455.
P0455 on other makes
Other codes on Ford vehicles
P0455 on a Ford: frequently asked questions
What does diagnostic trouble code P0455 mean on a Ford?
P0455 is set when the EVAP system's gross-leak monitor detects an opening approximately 0.090 inches (2.3 mm) or larger — or in many cases, no seal at all. This is the size of a missing gas cap, a disconnected hose, or a failed vent solenoid stuck open. The system cannot hold pressure or vacuum for the calibration period, so the ECM concludes a major leak. P0455 is a standardized OBD-II code, so the definition is the same on every Ford — which cause is most likely varies by model and engine.
What are the symptoms of P0455 on a Ford?
Check Engine Light is illuminated. Distinct fuel smell, especially after refueling. Fuel-cap warning message on the dashboard on some vehicles. No drivability issue. Vehicle will fail emissions / smog testing
What causes P0455 on a Ford?
Missing, loose, or wrong-fit fuel cap (most-common). Disconnected or split EVAP hose (common). EVAP vent valve stuck open (will not seal during the monitor test) (common). Damaged or rusted-through fuel filler neck (occasional). Cracked or broken EVAP charcoal canister (occasional). Damaged O-ring at the fuel pump assembly cover (rare). Rodent damage to EVAP hoses (parked vehicles) (occasional)
Is it safe to drive a Ford with P0455?
In most cases a Ford stays drivable for short trips with P0455 active, but it should be diagnosed and repaired promptly — this is a low-severity code. Ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.