P0455 on a Toyota Highlander
P0455 means evaporative Emission System Leak Detected (Large Leak). On the Highlander, a few causes come up far more than others.
What P0455 usually means on a Highlander
P0455 on a Highlander is a large EVAP leak — the system can't hold vapor pressure. The cheapest and most common cause is a loose or worn fuel cap, so that's the first thing to check. Beyond that, the charcoal canister, vent valve, and aging hoses are the typical failure points on these SUVs. There's no effect on drivability; it simply lights the dash and blocks emissions readiness.
Most common causes on the Highlander
- Loose or failed gas cap
A cap that won't click or has a hardened seal causes many Highlander P0455s and is a trivial fix.
- Charcoal canister leak
The tank-area canister cracks or loses its seal on high-mileage Highlanders.
- Vent valve stuck open
A vent solenoid that fails to close keeps the system from building the pressure the test needs.
- Cracked EVAP hoses
Underbody lines near the tank turn brittle and split with age, especially where salt is used.
What P0455 costs to fix on a Highlander
Try a genuine Toyota fuel cap first — it's a few dollars and often the entire fix. If the leak is deeper, the canister or vent valve is a moderate part but sits under the vehicle near the tank, adding labor. A smoke test pinpoints the leak so you don't replace parts by guesswork.
Year, engine and mileage change the answer. Start a case and Redline weighs these causes against what your car shows, then names the check that would settle it.
Highlander owners also ask
The light stayed on after I replaced the gas cap.
The Highlander re-runs its EVAP monitor over several drive cycles, so the code can take a few days to clear on its own, or a scan tool clears it right away. If it returns, the real leak is elsewhere in the system.
Does P0455 affect drivability?
It's lower urgency — an emissions leak in the fuel-vapor system rather than an engine fault. What it costs you is a lit warning light that can hide a new problem and a failed emissions readiness check, so get it fixed before inspection. If you smell raw fuel, get it checked promptly.
Other codes on the Toyota Highlander
Related symptoms
Toyota Highlander problems & recalls by year
Based on widely reported patterns for this model; individual causes vary by year, engine and history. Generic P0455 behavior is covered on the main P0455 page. Confirm with a scan tool before buying parts.
P0455 on your Highlander?
Every problem becomes a Case. Tell Redline what your Highlander is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.