The Quick Answer above is the generic definition. What follows is the model-specific detail for the Volkswagen models that log P0131.
DTC/P0131·Volkswagen
P0131 on Volkswagen: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Volkswagen
P0131 on a Volkswagen means the upstream oxygen sensor on bank 1 is reporting a voltage that stays too low, which the ECU reads as a lean exhaust. The cause can be on the sensor side (a failing sensor or its wiring) or a real lean condition such as a vacuum or exhaust leak. If the sensor is wrongly reporting lean, the ECU may add extra fuel and the engine can run rich. VW, Audi, Skoda and SEAT apps often show this code as P013100; the last two digits are a failure-type byte.
Typical repair cost, all makes€45 - €280
Connect any standard Bluetooth OBD2 adapter to your Volkswagen and Skanyx tells you what P0131 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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Volkswagen Golf
2005-2024Check whether your Golf's engine uses a wideband (air-fuel ratio) upstream sensor or a narrowband one before judging the live data or ordering parts: a wideband sensor does not switch between 0.1 and 0.9V and costs more. Vacuum leaks from the PCV system or intake manifold are common triggers on turbo engines.
What causes P0131 on a Volkswagen?
Beyond the generic causes listed on the main P0131 page, these are the patterns noted for Volkswagen models:
Volkswagen GolfPCV valve failure causing vacuum leak and lean condition
Volkswagen GolfUpstream sensor degradation on high-mileage TSI engines
How to diagnose P0131 on a Volkswagen with OBD2
Follow these steps to pinpoint the root cause of P0131:
- Use a scan tool to monitor the bank 1 sensor 1 signal in real time. A healthy narrowband sensor switches between about 0.1V and 0.9V, and a reading stuck low (below 0.2V) suggests a lean condition or sensor failure. Many newer engines use a wideband (air-fuel ratio) upstream sensor instead, which does not switch like this and is read as a lambda or equivalence-ratio value, so check which type your engine has
- Check for vacuum leaks by performing a smoke test or spraying propane around intake manifold gaskets, vacuum hoses, and the brake booster line. A leak causes real lean conditions
- Inspect the exhaust system between the engine and the O2 sensor for leaks. Cracked exhaust manifolds or loose connections allow outside air to reach the sensor, giving false lean readings
- Inspect the O2 sensor connector and wiring for corrosion, heat damage, or rodent chewing. Repair any wiring faults found
- If no leaks or wiring issues are found, replace the O2 sensor
How much does P0131 cost to fix on a Volkswagen? (EUR)
Estimated repair costs for P0131 in EUR, compiled across makes. Expect Volkswagen 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 P0131
These codes are often seen alongside P0131 or point to related issues, on any make:
Looking for the full P0131 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0131 guideSkanyx · Volkswagen
Diagnose P0131 on your Volkswagen
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