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P0447 on Audi: Causes, Symptoms and Fix Cost

Quick Answer

Safe to drive (short-term)

P0447 on a Audi means the ECU detected an open electrical circuit on the EVAP vent control valve. The vent valve seals the charcoal canister during EVAP system testing. An open circuit usually points to a broken wire, a corroded connector, or a failed solenoid coil inside the valve itself. VW, Audi, Skoda and SEAT apps often show this code as P044700; the last two digits are a failure-type byte.

Severity
Low · EVAP System
Typical repair cost, all makes
€50-€600

Connect a standard OBD2 adapter (Bluetooth LE on iPhone) to your Audi and Skanyx tells you what P0447 means on that engine, whether it is safe to keep driving, and what the fix should cost. Free on iPhone and Android.

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What does P0447 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 P0447.

Audi A4

2005-2024

On A4s with leak-detection hardware, the EVAP vent valve at the canister is the usual failure for P0447, and the harness is worth checking where it crosses the rear subframe. Aftermarket valves are sold by online parts retailers at around 40 to 60 EUR. 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

  1. publications.jrc.ec.europa.eu publications.jrc.ec.europa.eu/repository/bitstream/JRC77061/final_evap_report_on

What causes P0447 on a Audi?

Beyond the generic causes listed on the main P0447 page, these are the patterns noted for Audi models:

  • Vent valve failure at the canister

    : Audi A4

  • Harness chafing where it crosses the rear subframe

    : Audi A4

How to diagnose P0447 on a Audi with OBD2

  1. Locate the vent valve. On most vehicles it is bolted to the charcoal canister near the rear axle or fuel tank. Inspect the connector for corrosion, road salt damage, or a loose lock
  2. Disconnect the valve and measure solenoid resistance with a multimeter. Expect 20 to 35 ohms on most designs. An infinite reading confirms an open coil and a failed valve
  3. With the connector unplugged, probe the harness-side terminals for supply voltage (key on, engine off). Check a wiring diagram first: on a valve the ECU switches on the ground side, the supply comes up with the main relay and no reading at key-on can be normal, so confirm what the circuit should do before chasing a fault
  4. Inspect the wiring from the ECU to the vent valve for chafing, rodent damage, or breaks. The harness often runs along the underbody and is exposed to road debris
  5. Command the vent valve on and off with a diagnostic tool that supports actuator tests (often manufacturer-level software; a generic OBD2 reader usually cannot) and listen for a clear click. If the valve is silent and resistance is in spec, suspect a wiring or ECU fault

How much does P0447 cost to fix on a Audi? (EUR)

Estimated repair costs for P0447 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
Repair wiring or connector at vent valve €10–€40 €40–€120 €50–€160 Moderate
Replace EVAP vent valve solenoid €40–€150 €30–€80 €70–€230 Moderate
Replace charcoal canister with integrated vent valve €100–€400 €80–€200 €180–€600 Professional

Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.

These codes are often seen alongside P0447 or point to related issues, on any make:

Looking for the full P0447 reference (all makes, full diagnosis flow, complete repair cost matrix)? See the main P0447 guide

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