P0442 on a 2016 Chevy Silverado 1500: Small EVAP Leak

Code P0442 means a small EVAP leak. On a Chevy Silverado 1500, the gas cap is the cheapest and most common fix, then a smoke test.

Reviewed by Innova ElectronicsPublished 3 min read

What P0442 means on a 2016 Chevrolet Silverado 1500

Diagram of evap (evaporative emission) system: obd-ii port under the dash, purge valve engine bay, intake side, fuel cap rear quarter panel, filler neck rear underbody, charcoal canister near the fuel tank, vent valve at the canister, evap lines along the underbody. The charcoal canister is highlighted.
Charcoal canister — near the fuel tank. EVAP (evaporative emission) system: the sealed loop that captures fuel vapour from the tank and feeds it to the engine. Typical layout; exact positions vary by make and model.

Code P0442 on a 2016 Chevy Silverado 1500 points to a leak in the fuel vapor system. The truck's computer found a small leak in the EVAP system, the part of the fuel system that traps gas fumes and routes them to the engine instead of letting them escape into the air.

A small leak is most commonly a loose, worn, or cracked gas cap seal, followed by a cracked EVAP hose or a leaking purge valve seal.

Work safely

  • Unless a step says otherwise, work with the engine off and cool, the parking brake on, and the vehicle on level ground.
  • Keep sparks, flames and cigarettes away when you work near fuel or EVAP parts, and work in a well-ventilated place.
  • Wear safety glasses and gloves.
  • This guide doesn't replace your vehicle's service manual. If a step is beyond your tools or experience, have a shop do it.
7 steps

How to fix it, step by step

Step 1

Check the gas cap

Fig. 01 · Fuel capEnlarge
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Fuel cap — rear quarter panel. Typical layout; exact positions vary by make and model.
  • Check the gas cap first, and make sure it is tightened until it clicks 3 times.
  • If it is loose, worn, or the rubber seal looks cracked, replace it with a Stant Fuel Cap (OEM# 12630282).
  • Tip: If it is just the gas cap, the repair is under $20, DIY, and takes 5 minutes.
Step 2

Inspect the EVAP hoses

Fig. 02 · EVAP linesEnlarge
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EVAP lines — along the underbody. Typical layout; exact positions vary by make and model.
  • Visually inspect the EVAP hoses you can see under the hood and near the top of the fuel tank for cracks, chafing, or loose fittings.
  • Tip: A cracked hose is a common cause of small leaks.
Step 3

Smoke test the EVAP system

  • Smoke-test the whole EVAP system, or have a shop do it.
  • A smoke test pinpoints exactly where the leak is instead of guessing.
Step 4

Test the purge valve

Fig. 04 · Purge valveEnlarge
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Purge valve — engine bay, intake side. Typical layout; exact positions vary by make and model.
  • Inspect and test the EVAP purge valve. It should open and close cleanly with no vacuum leak when commanded.
Step 5

Test the canister vent valve

Fig. 05 · Vent valveEnlarge
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Vent valve — at the canister. Typical layout; exact positions vary by make and model.
  • Inspect and test the EVAP canister vent valve or solenoid.
  • Tip: A leaking seal here is a very common cause on these trucks.
Step 6

Check the filler neck and canister lines

Fig. 06 · Filler neckEnlarge
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Filler neck — rear underbody. Typical layout; exact positions vary by make and model.
  • Check the fuel tank filler neck and canister lines for rust-through or loose clamps, which is common near the frame rail.
Step 7

Replace the failed part and confirm the repair

  • Replace whichever component fails the smoke test, clear the code, and drive the truck to confirm the light stays off.

Parts you may need

  • Stant Fuel Cap (OEM# 12630282), about $15, only needed if the old cap seal is worn
  • ACDelco EVAP Canister Purge Valve (OEM# 12610560), about $40 to $60
  • ACDelco EVAP Canister Vent Valve (OEM# 25932542), about $40 to $70
  • Dorman EVAP Purge Valve, an alternative if going aftermarket

Tools

  • EVAP smoke test machine (a Dorman 911-001 smoke test adapter works with a rented smoke machine)
  • Basic socket set, for accessing hose clamps and canister mounting bolts
  • Flashlight or inspection mirror, to check hoses near the frame rail and fuel tank
  • Nitrile gloves and safety glasses

Common questions

What does P0442 mean on a Chevy Silverado 1500?
It means the computer found a small leak in the EVAP system, which traps gas fumes and routes them to the engine instead of letting them escape into the air.
What usually causes P0442 on a 2016 Silverado?
The most common cause is a loose, worn, or cracked gas cap seal, followed by a cracked EVAP hose or a leaking purge valve seal.
How much does it cost to fix P0442?
If it is just the gas cap, under $20 as a DIY job. If a purge or vent valve is confirmed bad by the smoke test, parts run $40 to $70, and shop labor is about 0.5 to 1 hour at $100 to $150 per hour, so $50 to $150 total if you do not do it yourself.
Can I replace the purge or vent valve myself?
Most vent and purge valves are a straightforward DIY swap.

The bottom line

Start with the gas cap, since it is the cheapest and most common fix for this exact code. If the light comes back on, move to a smoke test. Most P0442 cases resolve without needing to replace the canister or the fuel tank itself.

Based on AskFixy, Innova's repair assistant, and reviewed by Innova Electronics before publishing.