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BMW P0456: evaporative system small leak
The fuel vapour system failed its own leak test by a small margin. It doesn't affect how the car drives. On BMWs, check the fuel cap, then the leak detection module.
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Codes on this page
| Code | Definition | Source |
|---|---|---|
| P0456 | Evaporative emission system: small leak detected | Generic OBD-II |
| 190302 | Fuel tank ventilation and purge air system, micro leak: leakage greater than 0.5 mm | SI B16 15 14 (PDF) |
| 194006 | Tank leakage detection module, solenoid valve: jammed open | SI B16 04 17 (PDF) |
P-codes are the generic OBD-II codes any reader shows. Six-character and four-character hex codes are BMW's own, read with a BMW-capable scanner; the wording is BMW's, from the source shown.
What it means
The fuel tank vents its vapour into a charcoal canister, and the purge valve feeds it to the engine to burn. Many F- and G-series BMWs test that system with a Natural Vacuum Leak Detection (NVLD) module; older cars use a leak-test pump (DMTL). A small leak sets P0456 on a generic reader and 190302 on a BMW scanner. The EPA notes a loose or missing gas cap is a common trigger.
Can I keep driving?
Yes. An EVAP leak doesn't change how the car drives. It keeps the check engine light on, which can fail an emissions inspection and hide a new fault, so get it fixed.
Usual causes on BMWs
| Cause | Cars most affected | What you notice | Evidence | Repair prices (national average) |
|---|---|---|---|---|
| Fuel filler cap not sealing | All | The first thing to check; tighten it until it clicks or replace a worn seal. The light can take several drives to go out. | EPA | — |
| NVLD pressure switch or dust filter contaminated | F01, F02, F06, F07, F10, F12, F13, F15, F16, F22, F25, F30, F31 and others | 190302 stored with the check engine light. The BMW test plan may call for a new NVLD and its filter. | SI B16 15 14 (PDF) | — |
| NVLD solenoid jammed open or a vent-system leak | G30 5 Series (bulletin), others | 194006, often with 190302. BMW lists an unsealed filler cap, a faulty NVLD and a fuel tank leak as the possible sources. | SI B16 04 17 (PDF) | — |
| Purge (tank vent) valve or lines | B48, B58 and others | Leaking purge valve or cracked vent lines; often also gives rough idle after refuelling. | — | B58 / B48 fuel tank vent valve (purge valve) Indie $63–$173 Dealer $195–$285 |
A bulletin isn't a recall and doesn't mean your car has the problem; open it for the exact models and build dates. Estimates are national averages built from BMW warranty labor time, regional shop rates and parts prices; open a repair for your ZIP. "Owners paid" is the middle half of sourced prices, shown where we have at least 3.
What to do
- Check and reseat the fuel cap, then drive normally for a few days.
- If it returns, ask for a smoke test of the EVAP system before replacing parts.
- Ask about the plastic fuel tank emissions warranty extension on B46/B58/N20/N55/S55 cars before paying for a tank-related repair.
Warnings it can bring up
Related codes
Other BMW bulletins that mention it
- SI B01 03 22 Plastic fuel tank (B46/B58/N20/N55/S55) ltd wty ext (elw) 15 years/150,000 miles F22, F23, F30, F31, F32 and others · Oct 2024
- SI B16 01 23 Tank ventilation micro-leak diagnosis using nvld3 tester pn 83 30 5a39389 2024-01-05 G01, G02, G05, G06, G07 and others · Jan 2024
- SI B01 09 21 G01/02 G30/32 evap leak diagnosis system (NVLD) module ext ltd wty (elw) 15/150 G01, G02, G30, F97, F98 and others · Aug 2026
- SI B01 08 21 F9x S58 S63 evap leak diagnosis system (NVLD) module ext ltd wty (elw) 15/150 G01, G02, G05, G06, F90 and others · Dec 2024
- SI B01 15 24 G01/02 G30/32 evap leak diagnosis system (NVLD) module ext ltd wty (elw) 15/150 G05, G06, G07, G11, G12 and others · Jul 2026
- SI B01 04 16 N54 Tank Leak Diagnostic Module (DMTL) Pump: Limited Warranty Extension to 10 Years/120,000 Miles F01, F02 · Mar 2016
- SI B01 15 16 N26 leak diagnosis module (NVLD): limited warranty extension to 10 years/120,000 miles for “non-california… E92, E93, F22, F23, F30 and others · Aug 2016
- SI B01 10 16 N55 pressure switch - leak diagnosis module (NVLD): limited warranty extension to 10 years/120,000 miles F01, F02, F06, F07, F10 and others · Aug 2016
38 of the BMW bulletins we hold mention it in their text; these are the closest matches.
Sources
- OBD-Codes.com: P0456 definition
- US EPA: What to do with the check engine light (EPA420-F-00-041)
- NHTSA: BMW technical service bulletins and recalls by VIN
Bulletins are cited in the tables above. Explanations are ours; where a source is an owner report rather than BMW, it is labelled as one.