The Quick Answer above is the generic definition. What follows is the model-specific detail for the BMW models that log P0442.
DTC/P0442·BMW
P0442 on BMW: Causes, Symptoms and Fix Cost
Quick Answer
Low SeveritySafe to drive (short-term)BMW
P0442 on a BMW means the engine control unit has detected a small leak in the evaporative emission control system. This system captures fuel vapours from the tank and routes them to the engine to be burned. A small leak allows vapours to escape, increasing hydrocarbon emissions.
Typical repair cost, all makes€10 - €450
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BMW 3 Series
2006-2024BMWs with an EVAP leak test use a leak detection pump (LDP, called DMTL on many models) to pressurise the system. A failing pump can falsely trigger P0442 even when there is no actual leak, and the fuel tank vent valve on E90 models is also worth checking.
What causes P0442 on a BMW?
Beyond the generic causes listed on the main P0442 page, these are the patterns noted for BMW models:
BMW 3 SeriesFailing leak detection pump giving false positive
BMW 3 SeriesFuel tank vent valve failure on E90 models
How to diagnose P0442 on a BMW with OBD2
Follow these steps to pinpoint the root cause of P0442:
- Check the fuel cap first. Remove it, inspect the rubber seal for cracks or debris, and re-seat it until it clicks. Clear the code and drive for a few days to see if it returns
- Visually inspect all EVAP hoses from the fuel tank to the charcoal canister and from the canister to the purge valve at the engine. Look for cracks, loose clamps, or disconnections
- Perform a smoke test on the EVAP system by sealing the system and introducing smoke. Watch for smoke escaping at hose connections, the canister, or the fuel tank area
- Test the purge valve and vent valve by commanding them open and closed with a diagnostic tool that supports actuator tests (on many cars this needs manufacturer-level software, not a generic OBD2 reader). A stuck-open purge valve can allow ambient air into the system, mimicking a leak
- If the smoke test reveals no external leaks, inspect the charcoal canister for cracks and the fuel tank for damage, particularly around the fuel pump module seal
How much does P0442 cost to fix on a BMW? (EUR)
Estimated repair costs for P0442 in EUR, compiled across makes. Expect BMW parts and labour towards the upper end of each range.
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
Codes related to P0442
These codes are often seen alongside P0442 or point to related issues, on any make:
Looking for the full P0442 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0442 guideSkanyx · BMW
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