P0455 on Chevrolet: How to Diagnose & Fix

The HHR has a documented issue with fuel line corrosion, particularly in rust belt states. The fuel line corrodes just forward of the driver-side rear wheel, developing leaks that create a fire hazard. Road salt and debris accelerate the corrosion. The issue is most commonly seen on vehicles in the northeastern and midwestern United States where road salt is used heavily in winter.

The C7 uses a saddle-style twin fuel tank. On 2014-2017 cars, cracks develop on the top surface of the left-hand fuel tank's primary fuel pump module flange, allowing liquid fuel and vapor to escape. Owners report a strong fuel smell - most obvious after parking a full car in a closed garage - and in worse cases fuel dripping onto the ground beneath the left rear of the car. The flange sits on top of the tank, so the leak is invisible without lifting the car, and the smell is often blamed on the evaporative system or the filler neck. Because the leak point is above the fuel level, the odor and drip typically appear when the tank is more than half full, and a check engine light may set when the level drops below half. This is a fire risk and GM established Special Coverage 17469 with unusually long terms - 10 years or 120,000 miles from the in-service date, regardless of ownership.

P0455 indicates a large EVAP leak (a hole ~0.040 inch or bigger). On the Malibu the leading cause — more than half of cases across GM cars of this era — is a loose, missing, or failed fuel cap (or, on 2016+ capless cars, a bad filler-neck seal). The second most common cause is a failed EVAP purge valve stuck open, a notoriously common GM failure shared across the Impala, Camaro, and others. Cracked or disconnected canister/vent hoses can also let enough vapor escape to trip the gross-leak monitor.

Owners of the seventh- and eighth-generation Malibu report a fuel gauge that reads wrong in a specific, repeatable way: fill the tank and it shows three-quarters, or the needle sits above empty while the car runs out of fuel. GM addressed one root cause in a service bulletin — the fuel vapor line inside the tank is routed so that it physically interferes with the travel of the fuel level sender float arm, pinning the sender at an intermediate position. The other cause is the sender card itself, where the wiper contacts wear a dead spot in the resistive track and the gauge sticks or drops to empty. The bulletin also ties the condition to EVAP codes, because the same in-tank plumbing is involved; a P0461 (fuel level sensor range/performance) is the signature code. This is more than an annoyance on this car — the fuel-level input feeds the EVAP diagnostic and the range calculation, so a stuck sender leaves owners stranded.

The vapor-canister purge solenoid on the V6 Equinox (and Terrain) commonly fails stuck-open, letting fuel vapor flow into the intake when it shouldn't. This sets DTC P0496 (EVAP flow during a non-purge condition) and sometimes P0455/P0446, illuminates the check-engine light, and can cause a rough/rich idle, hard starting, and even a faint fuel smell. It is one of the most frequently replaced emissions parts on the V6 Equinox because the valve is a known weak point and the repair is cheap and easy. The valve sits on top of the engine and is a roughly one-hour DIY job.

A very common GMT800 Silverado problem is contamination of the EVAP canister vent valve/solenoid by dust, road debris, or water intrusion. When the vent cannot flow properly, the truck sets EVAP leak or vent performance codes and may repeatedly shut off the gas pump during refueling. GM issued service bulletins and updated vent relocation kits for trucks used in dusty environments.

First-generation Colorado trucks frequently develop EVAP system faults because the vent valve and canister are mounted in an area exposed to dust, dirt, and road debris. Contamination can clog the vent path or stick the valve, triggering a check engine light and causing the fuel nozzle to click off repeatedly during refueling. This issue is especially common on trucks used on gravel roads or in dusty environments.

On the 3.6L V6 (RPO LFY) Traverse, the evaporative emissions purge valve can fail to fully close, allowing fuel vapor to flood the intake. This causes a P0496 (EVAP high purge flow) code with rough running, hesitation, or stalling at idle, and hard starting after refueling. GM acknowledged the condition and issued Special Coverage N232395300 (15 years / 150,000 miles) to replace the purge valve at no charge on affected 2019 Traverse units.