P0457 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Safe to drive (short-term)
P0457 on a Audi means the ECU detected an evaporative system leak consistent with a loose, missing, or damaged fuel cap. The code is specifically tuned to flag cap-sized leaks before flagging generic small (P0442) or large (P0455) leaks. The first thing to check is always the cap itself.
- Severity
- Low · EVAP System
Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your Audi and Skanyx tells you what P0457 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.
Get Skanyx freeWhat does P0457 mean on a Audi?
The Quick Answer above is the generic definition. What follows is the model-specific detail for the Audi models that log P0457.
Audi A4
2005-2024
The A4 cap, like the Golf's, must be turned until it clicks, and a cap not seated properly at refuelling is the usual cause of P0457. Anyone who refuels the car should turn the cap to the click. Many European-market cars are built to EU on-board diagnostic rules, which only require the purge valve circuit to be checked rather than the system to be tested for leaks, so check that your car actually has leak-detection hardware before chasing this code.
Source: publications.jrc.ec.europa.eu
Sources
- publications.jrc.ec.europa.eu publications.jrc.ec.europa.eu/repository/bitstream/JRC77061/final_evap_report_on
What causes P0457 on a Audi?
Beyond the generic causes listed on the main P0457 page, these are the patterns noted for Audi models:
Bayonet cap not seated properly at refuelling
: Audi A4
Worn cap seal at 100,000+ km
: Audi A4
How to diagnose P0457 on a Audi with OBD2
- Remove the fuel cap and inspect the rubber seal for cracks, brittleness, or debris. If the seal compresses unevenly when squeezed, replace the cap
- Re-seat the cap and tighten until it clicks. Clear the code and drive for 3 to 5 cycles to let the EVAP monitor retest
- If the code returns with a known good cap, inspect the fuel filler neck. Look for damage to the threads or to the sealing surface where the cap meets the neck
- On capless filler systems (such as Ford Easy Fuel), inspect the flapper assembly for debris, damaged seals, or a stuck flapper. Clean carefully or replace the assembly if damaged
- If the cap and filler neck are good, perform a smoke test focusing on the upper portion of the EVAP system. A leak at the tank top or fuel pump module gasket can mimic a cap leak
How much does P0457 cost to fix on a Audi? (EUR)
Estimated repair costs for P0457 in EUR, compiled across makes. Expect Audi parts and labour towards the upper end of each range.
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Tighten existing fuel cap (free fix) | €0–€0 | €0–€0 | €0–€0 | Easy |
| Replace fuel cap | €10–€40 | €0–€0 | €10–€40 | Easy |
| Replace fuel filler neck or capless flapper assembly | €80–€300 | €80–€200 | €160–€500 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Codes related to P0457
These codes are often seen alongside P0457 or point to related issues, on any make:
Looking for the full P0457 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0457 guide