P0442 on GMC
Evaporative Emission Control System Leak Detected (Small Leak)
P0442 on GMC vehicles indicates evaporative emission control system leak detected (small leak). Au7o has documented this code across 1 GMC model — most commonly on Sierra 1500. This emissions code means the evaporative emission (EVAP) control system has detected a small leak. The EVAP system seals the fuel tank and captures gasoline vapors, routing them to be burned in the engine instead of escaping into the air, and the computer periodically pressure- or vacuum-tests the system to confirm it's sealed. A small leak the size of about a 0.040-inch hole will set this code. By far the most common and cheapest cause is a loose, damaged, or missing gas cap, so that's the first thing to check, though any cracked hose or worn seal in the system can also trigger it. Typical repair costs on GMC range from $20 to $250, depending on the specific model and root cause.
Common Causes of P0442
- •Loose, damaged, or missing fuel filler cap
- •Worn or cracked gas cap seal
- •Cracked or disconnected EVAP hose or line
- •Faulty purge valve or vent valve
- •Damaged O-ring or seal at the fuel tank or filler neck
- •Small crack in the charcoal canister
- •Leaking fuel tank sending unit gasket
P0442 on GMC by Model
GMC Sierra 1500(1 issue)
- P0442 — Small EVAP Leak from Loose/Cracked Gas Cap or Fractured Filler Vent Hose2007-2018
P0442 on the Sierra 1500 is a small EVAP leak detected during the ECM's key-off/idle vacuum test. On these trucks the two most common real-world causes are a loose, worn, or cracked gas cap seal (the cheapest fix and always the first check) and — a documented GM issue (TSB 15-NA-019) — the fuel tank filler vent hose connector cracking, which allows vapor to escape and sets P0442 (and sometimes P0455). The vent hose fracture is addressed by replacing the vent hose assembly (part No. 22802073 on 2013-2015 models). The EVAP purge valve (engine bay) and vent solenoid (near the tank) can also weep. Drivers often notice a faint fuel odor and the CEL, with no drivability change.
Looking for P0442 on a different make?
View P0442 across all makes →Frequently Asked Questions
What does P0442 mean on GMC?▼
P0442 stands for "Evaporative Emission Control System Leak Detected (Small Leak)." This emissions code means the evaporative emission (EVAP) control system has detected a small leak. The EVAP system seals the fuel tank and captures gasoline vapors, routing them to be burned in the engine instead of escaping into the air, and the computer periodically pressure- or vacuum-tests the system to confirm it's sealed. A small leak the size of about a 0.040-inch hole will set this code. By far the most common and cheapest cause is a loose, damaged, or missing gas cap, so that's the first thing to check, though any cracked hose or worn seal in the system can also trigger it. On GMC specifically, this code is documented across 1 model.
What causes P0442 on GMC vehicles?▼
Common causes on GMC: Loose, damaged, or missing fuel filler cap, Worn or cracked gas cap seal, Cracked or disconnected EVAP hose or line, Faulty purge valve or vent valve, Damaged O-ring or seal at the fuel tank or filler neck. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0442 on a GMC?▼
Repair costs on GMC range from $20 to $250, depending on the specific model and root cause.
Which GMC models have P0442 documented?▼
Au7o has documented P0442 on 1 GMC model: Sierra 1500.