Jeep Grand Cherokee P0455

Quick answer: P0455 on your Jeep Grand Cherokee means the powertrain computer detected a large leak in the EVAP (evaporative emissions) system, which captures fuel vapors and prevents them from escaping into the air. On the Grand Cherokee this is most often a loose, cross-threaded, or worn gas cap, but it can also be a cracked EVAP hose, a stuck purge or vent valve, or a failing leak-detection pump. It is a low-severity code: you can keep driving safely, though you should not ignore it, since it will keep the check-engine light on and cause an emissions-test failure.

TL;DR

P0455 is a large EVAP leak. On the Grand Cherokee it is usually a loose or worn gas cap, a cracked EVAP hose, or a stuck purge/vent valve. Low severity, safe to drive.

Why P0455 shows up on the Jeep Grand Cherokee

The Grand Cherokee uses a sealed EVAP system that stores fuel vapors in a charcoal canister and later burns them in the engine. When the computer runs a self-test and cannot build or hold the expected pressure or vacuum, it logs P0455 for a large leak. Because this SUV spends a lot of time on rough trails, dusty roads, and through temperature swings, the rubber EVAP lines and valve seals age faster than on a commuter car, which is why this code is fairly common on higher-mileage examples.

Model-typical causes and rough likelihood

Gas cap (about 30-40%) — loose, not clicked, cross-threaded, or a hardened seal. Always check this first.
Cracked or disconnected EVAP hose (about 20-30%) — lines near the canister and along the frame get brittle and chafe.
Purge valve or vent valve stuck open (about 20%) — commonly reported, especially where the vent valve collects trail dust.
Leak-detection pump or canister fault (about 10-15%) — less frequent but worth testing if the basics are fine.

Owner tips before you pay for diagnosis

Open the fuel door, remove the gas cap, inspect the rubber seal for cracks, and re-tighten until it clicks several times. Drive a few days and see if the light clears on its own. Avoid topping off the tank past the first click, since overfilling can flood the EVAP canister and trigger this code. If the light stays on, a shop can use a smoke test to pinpoint the leak quickly.

Summary

Code	P0455
Meaning	EVAP System Leak Detected (Large Leak)
Severity	Low
Can I drive?	Yes, safe to drive
Most common cause	Loose or worn gas cap
Typical repair cost	$15-$600 (gas cap to canister)

Full diagnostics

For the complete step-by-step diagnostic and repair guide, see P0455 — full diagnostics.

Frequently asked questions

Is it safe to drive my Jeep Grand Cherokee with a P0455 code?

Yes. P0455 is a low-severity emissions code on the Jeep Grand Cherokee and does not affect engine power, braking, or safety. You can drive normally, but you should have the leak fixed soon because the check-engine light will stay on, you may fail an emissions test, and fuel vapors escaping to the atmosphere are wasteful and bad for the environment.

What is the most common cause of P0455 on a Jeep Grand Cherokee?

The most common cause on the Grand Cherokee is a loose, worn, or improperly sealed gas cap, which accounts for roughly a third of cases. After that, the usual culprits are a cracked or disconnected EVAP hose and a purge or vent valve stuck open. Because the Grand Cherokee is often driven on dusty trails, the vent valve and rubber lines wear faster than average.

How much does it cost to fix P0455 on a Jeep Grand Cherokee?

If it is only the gas cap, a replacement runs about 15 to 45 USD and you can install it yourself. A cracked EVAP hose repair typically costs 100 to 250 USD, while replacing a purge or vent valve usually runs 150 to 400 USD including labor. A leak-detection pump or canister replacement is the most expensive, often 300 to 600 USD.