P0440 is the generic OBD-II code for an evaporative emission control system malfunction. It means the ECU detected a fault in the system that captures fuel vapours from the tank and routes them to the engine. The most common trigger is a loose or missing fuel cap, but it can also indicate hose leaks, a failed purge valve, or a cracked charcoal canister.
DTC/P0440·Audi
P0440 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Low SeveritySafe to drive (short-term)Audi
P0440 on a Audi is the generic OBD-II code for an evaporative emission control system malfunction. It means the ECU detected a fault in the system that captures fuel vapours from the tank and routes them to the engine. The most common trigger is a loose or missing fuel cap, but it can also indicate hose leaks, a failed purge valve, or a cracked charcoal canister.
Repair cost on Audi€13 - €750
What does P0440 mean on a Audi?
Audi A4
2005–2024The B7 and B8 A4 with the 2.0 TFSI EA888 engine commonly trigger P0440 due to the N80 purge valve clicking loudly and failing in the open position. The valve is mounted on the intake manifold and is replaceable in under 30 minutes. A loud ticking from the engine bay is the classic symptom before the code sets.
What causes P0440 on a Audi?
Beyond the generic causes listed on the main P0440 page, these are the Audi-specific patterns we see most often:
Audi A4N80 purge valve clicking and failing on B7/B8 2.0 TFSI
Audi A4Brittle EVAP hoses near the engine from heat cycling
How to diagnose P0440 on a Audi with OBD2
Follow these steps to pinpoint the root cause of P0440:
- 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 several cycles to see if it returns
- Visually inspect EVAP hoses from the fuel tank to the charcoal canister and from the canister to the purge valve at the engine. Look for cracks, brittle plastic, loose clamps, or disconnections
- Perform a smoke test on the EVAP system. Seal the system, introduce smoke, and watch for visible plumes escaping at hose connections, the canister, or the fuel tank area. Expect 40 to 100 EUR for the diagnostic alone at a workshop
- Use a scan tool to command the purge valve and vent valve open and closed. Listen for clicking. A stuck-open or stuck-closed valve is a frequent cause
- If the smoke test reveals no external leaks, inspect the charcoal canister for cracks and check the fuel tank pressure sensor reading with live data
How much does P0440 cost to fix on a Audi? (EUR)
Estimated repair costs on a Audi (Audi parts and labour typically run 25% above the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0440 on Audi
These codes commonly cluster with P0440 on Audi vehicles:
FAQ: P0440 on Audi
Will P0440 fail my emissions test?
Yes. Any active OBD-II code with the check engine light on causes an automatic fail at EU vehicle inspections (TÜV in Germany, ITV in Spain, TA in Lithuania, SKP in Poland). You must clear the underlying fault before retesting.
Can a loose fuel cap really trigger P0440?
Yes, and it is the most common cause. The EVAP system is sealed, so even a small gap at the cap allows vapours to escape and the ECU registers a leak. Always tighten the cap until it clicks. Replace it if the rubber seal is cracked or compressed.
How long until P0440 clears after I fix it?
Once you tighten or replace the fuel cap, it takes 3 to 5 complete drive cycles for the ECU to retest the EVAP system and clear the code automatically. A drive cycle includes a cold start, mixed driving, and shutdown. You can also clear it manually with a scan tool.
What is the difference between P0440 and P0442?
P0440 is the generic EVAP malfunction code, often the first one set when the ECU detects something is wrong. P0442 specifically indicates a small leak (under 1mm equivalent orifice). Many vehicles set both codes together, with P0442 being more specific about the leak size.
Looking for the full P0440 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0440 guideSkanyx · Audi
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