The Quick Answer above is the generic definition. What follows is the model-specific detail for the Audi models that log P0158.
DTC/P0158·Audi
P0158 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Audi
P0158 on a Audi means the Bank 2 downstream oxygen sensor (after the catalytic converter, Sensor 2) is reporting a voltage that stays too high for too long, above roughly 1.0V. Bank 2 is the half of the engine without cylinder 1, found on most V6 and V8 engines, flat-six engines and a few straight sixes with a split exhaust. A healthy downstream sensor reads around 0.6-0.8V steady, so a persistently high reading usually means that bank is running rich, the signal wire is shorted to voltage, or the sensor is contaminated.
Typical repair cost, all makes€60 - €650
Connect any standard Bluetooth OBD2 adapter to your Audi and Skanyx tells you what P0158 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 P0158 mean on a Audi?
Audi A6
2004-2009The 3.2 V6 FSI runs separate oxygen sensing for each bank, so a rich condition on the bank 2 cylinders (4-6) raises the G131 reading while bank 1 stays normal, often alongside P0175. Check bank 2 fuel trims and look for an injector fault on that bank before replacing G131.
What causes P0158 on a Audi?
Beyond the generic causes listed on the main P0158 page, these are the patterns noted for Audi models:
Audi A6Rich running on cylinders 4-6
Audi A6Failed or contaminated G131 sensor
How to diagnose P0158 on a Audi with OBD2
Follow these steps to pinpoint the root cause of P0158:
- Confirm which sensor the code means before buying parts: Bank 2 is the cylinder bank that does not contain cylinder 1, and Sensor 2 is the one after the catalytic converter. Check the cylinder numbering for your engine in the service information, because the side of the car bank 2 sits on is not the same on every engine
- Read freeze frame data and check for companion codes (P0175, P0172, P0430) that point to a real rich condition or a converter problem
- Use a scan tool to view the downstream sensor voltage. A reading stuck near or above 1.0V at idle indicates a rich condition or a faulty sensor
- Compare long-term fuel trims on bank 1 and bank 2. If bank 2 is taking a lot more fuel away (strongly negative, under about -10%), that bank is genuinely running rich
- If bank 2 is rich, look at the bank 2 cylinders: misfire counters, injector leakage and spark plug condition on that bank
- Inspect the Bank 2 Sensor 2 signal wire for shorts to voltage, especially near heat shields and where the harness runs close to other power wiring
- Substitute a known-good sensor. If high voltage persists, the issue is fuel mixture or wiring, not the sensor
How much does P0158 cost to fix on a Audi? (EUR)
Estimated repair costs for P0158 in EUR, compiled across makes. Expect Audi 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 P0158
These codes are often seen alongside P0158 or point to related issues, on any make:
Looking for the full P0158 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0158 guideSkanyx · Audi
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