Ask Andy AIP0442 Evaporative Emission System Leak Detected (Small Leak)
What it means, what causes it, and what it costs to fix.
What P0442 means
Your EVAP system traps gasoline vapor from the tank and burns it in the engine instead of venting it outside. The computer seals the system and checks whether it holds vacuum or pressure. P0442 means it found a small leak, roughly the size of a 0.040-inch hole.
Can I drive with P0442?
Severity: Low. Not urgent. Fix it when convenient.
Safe to drive. This is an emissions leak, not a running problem. You may smell fuel, and you'll fail an emissions inspection until it's fixed.
Get a diagnosis for your exact car
Tell Andy your year, make, model, and symptoms. You'll get best case, most likely, and worst case, with parts and labor costs. Free, in about 15 seconds.
Ask Andy about P0442Symptoms
- Check engine light
- Faint fuel smell, especially near the rear of the car
- No drivability change
Common causes
Most likely first.
- Loose, worn, or wrong gas cap (most common)
- Cracked EVAP hose or connection
- Leaking purge or vent valve
- Cracked charcoal canister
- Leaking fuel filler neck
How to diagnose P0442
- Check the gas cap seal first. Tighten it until it clicks, or replace it with an OEM cap. Then clear the code and drive for a few days.
- If it returns, a shop can smoke-test the EVAP system to find the leak.
- Inspect hoses near the tank, canister, and filler neck for cracks.
Tip: most US auto parts stores will read your codes for free.
Repair costs
| Gas cap | $15–$40 |
| EVAP hose | $50–$200 installed |
| Purge or vent valve | $100–$350 installed |
| Charcoal canister | $250–$700 installed |
Typical US prices. Your vehicle, region, and shop rates will change these.
P0442 FAQ
What does P0442 mean?
P0442 means "Evaporative Emission System Leak Detected (Small Leak)." Your EVAP system traps gasoline vapor from the tank and burns it in the engine instead of venting it outside. The computer seals the system and checks whether it holds vacuum or pressure. P0442 means it found a small leak, roughly the size of a 0.040-inch hole.
Can I drive with a P0442 code?
Safe to drive. This is an emissions leak, not a running problem. You may smell fuel, and you'll fail an emissions inspection until it's fixed.
What is the most common cause of P0442?
The most common cause is: Loose, worn, or wrong gas cap. Other causes include cracked evap hose or connection and leaking purge or vent valve.
How much does it cost to fix P0442?
Typical repairs run about $15 to $700 in the US, depending on the cause. Gas cap: $15–$40.
Still not sure what's wrong?
Describe the noise, smell, or warning light, or snap a photo. Andy is free to try.
Ask Andy free