P0442 on Jeep: How to Diagnose & Fix
Evaporative Emission Control System Leak Detected (Small Leak)
2 Jeep models · 2 documented issues · $25-$350 repair
P0442 on Jeep by model: symptoms, diagnosis and fix
P0442 (small EVAP leak, roughly a 0.020–0.040 inch pinhole) is very common on the WK2 Grand Cherokee. The two dominant causes are a degraded gas cap rubber seal and, specific to this platform, a failed Evaporative System Integrity Module (ESIM) mounted in the rear driver-side wheel well. The ESIM is a well-documented WK2 failure point and often fails before other EVAP components; it is known to pass a smoke test yet still set the code because its internal switch fails to report the correct state to the PCM. A vapor canister purge valve stuck slightly open is a secondary cause. There are typically no drivability symptoms beyond the check engine light, and the code can be intermittent (may clear after a few good drive cycles once the cap is tightened).
Common Symptoms
- Check engine light on
- Intermittent fuel/vapor smell (rare)
- No noticeable drivability change
- Occasional gas cap warning
How to Fix
Start with a new OEM Mopar gas cap and confirm it clicks/seals; clear the code and drive several cycles. If it returns, replace the ESIM in the rear driver-side wheel well (accessed behind the fender liner, on the charcoal canister). If still present, smoke-test the EVAP system to find hose/purge-valve/canister leaks.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar evaporative-system integrity module (ESIM) for the confirmed 2016-2018 branchOEMMopar 68505622AA
Confirm the VIN, fuel-system configuration, connector and current part before purchase; it is not approved across the ful
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Sources for this issue (4)
P0442 on the Wrangler flags a small (~0.020-0.040 in) leak in the evaporative emissions system. On these Jeeps the two most common real-world sources are a loose, worn, or cracked fuel cap seal and a cracked rubber elbow/vent hose at the charcoal canister near the rear of the vehicle. Wranglers see a lot of trail dust, water crossings, and vibration, which ages the small rubber EVAP elbows and the o-ring on the fuel cap. Less commonly the purge valve, leak-detection pump, or the filler neck itself is the culprit. The code is emissions-only and typically causes no drivability problem, but it will fail an emissions/inspection test.
Common Symptoms
- Check engine light on
- Occasional faint fuel/gas odor
- No noticeable drivability change
- Fails emissions/inspection test
How to Fix
Start with the cheapest checks: make sure the fuel cap is clicked tight and inspect (or simply replace) the cap and its o-ring. If the code returns, smoke-test the EVAP system to pinpoint the leak — pay special attention to the vapor lines and the rubber elbow at the charcoal canister and to the purge and vent valves. Replace the failed cap, hose, valve, or canister as found and clear the code; the readiness monitor needs a few drive cycles to reset.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 52030387AB fuel-filler capOEMMopar 52030387AB
Replace a damaged or leaking cap after cap-seal and filler-neck inspection Fitment/availability: 2007-2018 Wrangler JK 3.8L/3.6L; distinguish 2018 JK from JL by VIN/body.
- Genuine Mopar 68339342AA fuel-filler capOEMMopar 68339342AA
Replace a damaged or leaking cap on the applicable JL branch Fitment/availability: 2018-2019 and 2021 Wrangler JL 2.0L or 3.6L as cataloged; verify VIN.
- Genuine Mopar 68484447AA fuel-filler capOEMMopar 68484447AA
Replace a damaged or leaking cap on the 2020 JL gasoline branch Fitment/availability: 2020 Wrangler JL 2.0L or 3.6L only; verify VIN. Fitment/availability: $34.31 shown; verify current checkout availability before ordering
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (4)
P0442 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0442 mean on a Jeep?
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 Jeep it is documented across 2 models: Grand Cherokee, Wrangler.
What are the most common causes of P0442?
The most common causes of P0442 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P0442 on a Jeep?
Published repair estimates on Jeep range from $25 to $350 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0442 on a different make?
View P0442 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.