Moderate SeveritySafe to drive (short-term)Fuel System
P0175 means the air-fuel mixture on Bank 2 is too rich and the ECU cannot remove enough fuel to bring it back to the 14.7:1 stoichiometric target. Because the code is bank-specific, the cause is usually something local to Bank 2 (a leaking injector on that side, a degraded sensor, or fuel pressure imbalances) rather than a whole-engine issue.
Estimated repair costFrom €120 to €600+, varies by vehicle
What does P0175 mean?
P0175 means the air-fuel mixture on Bank 2 is too rich and the ECU cannot remove enough fuel to bring it back to the 14.7:1 stoichiometric target. Because the code is bank-specific, the cause is usually something local to Bank 2 (a leaking injector on that side, a degraded sensor, or fuel pressure imbalances) rather than a whole-engine issue.
P0175 is a fuel system-related diagnostic trouble code classified as moderate severity. When your vehicle's ECU detects this condition, it stores P0175 and illuminates the check engine light.
What are the symptoms of P0175?
If your vehicle has triggered P0175, you may notice one or more of these symptoms:
Check engine light on
Reduced fuel economy
Strong fuel smell from the exhaust
Black soot at the tailpipe outlets, sometimes only on one side
Rough idle and possible cylinder-bank misfires
What causes P0175?
Here are the most common causes of P0175, ranked by how likely they are to be the culprit:
highLeaking injector on Bank 2
highFaulty Bank 2 upstream lambda sensor sending false lean reading
mediumHigh fuel pressure due to regulator imbalance
mediumCarbon-loaded EVAP system feeding extra vapour to Bank 2
lowDamaged Bank 2 wiring affecting injector pulse width
Is it safe to drive with P0175?
Generally yes, for short-term driving. Short-term driving is safe, but a rich-running bank wastes fuel, fouls plugs on that side, and gradually damages the catalytic converter on Bank 2. Fix within a couple of weeks to avoid catalyst replacement costs.
How do you diagnose P0175?
Follow these steps to pinpoint the root cause of P0175:
Read live data: confirm Bank 2 long-term fuel trim is negative beyond -20% while Bank 1 stays within normal range
Pull Bank 2 spark plugs and inspect for black sooty deposits. Compare to Bank 1 plugs; a clear visual difference confirms the bank-specific richness
Swap the upstream lambda sensors between Bank 1 and Bank 2. If the rich condition follows the sensor, replace it
Measure fuel pressure with a gauge and compare to spec at idle and under load. High pressure can over-fuel both banks but sometimes shows up more on the bank with already weak injectors
Perform an injector balance test or have injectors flow-tested off the engine. A single leaking injector on Bank 2 explains the code on a V6 or V8
How much does P0175 cost to fix?
Repair costs for P0175 vary depending on the root cause and your vehicle. Here are typical estimates:
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace Bank 2 upstream lambda sensor
€60–€200
€60–€150
€120–€350
Moderate
Replace or clean Bank 2 fuel injector
€60–€250
€100–€350
€160–€600
Professional
Replace fuel pressure regulator
€50–€200
€80–€250
€130–€450
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0175 on specific vehicles
P0175 behaves differently depending on your vehicle. Select your car below for model-specific causes, known issues, and adjusted cost estimates:
P0175 on BMW 3 Series
BMW 3 Series • 2006-2015
Earlier 3 Series with the N62 V8 and the legacy M3 V8 logged P0175 most often from a single leaking injector on Bank 2. BMW recommends replacing injectors as a set because the rich-running side is often the first symptom of broader wear. On N54 inline-six the code does not apply (single bank).
What causes P0175 on a BMW 3 Series?
BMW 3 SeriesLeaking Bank 2 injector on N62 V8
BMW 3 SeriesAged Bank 2 upstream lambda sensor on legacy V8 3 Series
P0175 repair cost for BMW 3 Series
Estimated costs for BMW 3 Series ownersadjusted higher than average due to BMW-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace Bank 2 upstream lambda sensor
€84–€280
€84–€210
€168–€490
Moderate
Replace or clean Bank 2 fuel injector
€84–€350
€140–€490
€224–€840
Professional
Replace fuel pressure regulator
€70–€280
€112–€350
€182–€630
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0175 on Audi A6
Audi A6 • 2011-2024
C7 A6 with the 3.0 TFSI sometimes logs P0175 when the EVAP purge valve sticks open and feeds extra vapour into the intake, but the manifold geometry biases the vapour toward Bank 2. A new purge valve usually resolves it without needing injector work.
What causes P0175 on a Audi A6?
Audi A6EVAP purge valve stuck open biasing vapour toward Bank 2
Audi A6Bank 2 injector seat wear after high mileage
P0175 repair cost for Audi A6
Estimated costs for Audi A6 ownersadjusted higher than average due to Audi-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace Bank 2 upstream lambda sensor
€78–€260
€78–€195
€156–€455
Moderate
Replace or clean Bank 2 fuel injector
€78–€325
€130–€455
€208–€780
Professional
Replace fuel pressure regulator
€65–€260
€104–€325
€169–€585
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0175 on Mercedes E-Class
Mercedes-Benz E-Class • 2011-2024
W212 E-Class with the M276 V6 logs P0175 most often from a stuck-open Bank 2 injector at high mileage. Mercedes updated injector internals mid-production. Replacement requires removing the intake plenum.
What causes P0175 on a Mercedes E-Class?
Mercedes E-ClassBank 2 injector internal leak on M276
Mercedes E-ClassBank 2 lambda sensor lazy response after 150,000 km
P0175 repair cost for Mercedes E-Class
Estimated costs for Mercedes E-Class ownersadjusted higher than average due to Mercedes-Benz-specific parts pricing
Repair
Parts Cost
Labor Cost
Total Estimate
DIY Difficulty
Replace Bank 2 upstream lambda sensor
€84–€280
€84–€210
€168–€490
Moderate
Replace or clean Bank 2 fuel injector
€84–€350
€140–€490
€224–€840
Professional
Replace fuel pressure regulator
€70–€280
€112–€350
€182–€630
Professional
Prices estimated as of March 2026. Costs vary by region, vehicle, and shop.
P0175 on Volkswagen Touareg
Volkswagen Touareg • 2010-2024
Touareg with the 3.0 TFSI V6 typically sets P0175 after a Bank 2 injector starts seeping at idle. Replacement is labour-intensive because of the tight bay, but the parts are common across the VAG 3.0 TFSI family.
What causes P0175 on a Volkswagen Touareg?
Volkswagen TouaregBank 2 injector seep on 3.0 TFSI Touareg
Single-bank rich codes usually trace to one component that affects only that bank: a leaking injector, a degraded upstream lambda sensor, or a vacuum imbalance. Whole-engine problems like high fuel pressure usually push both banks rich together.
Is black smoke from the exhaust dangerous?
Black smoke means unburned fuel is reaching the catalytic converter. Short-term it is not dangerous, but extended driving in this state can overheat and destroy the converter, which is by far the most expensive part of fixing P0175.
Can a bad lambda sensor cause P0175?
Yes. A lazy or biased upstream sensor on Bank 2 can report lean even when the mixture is correct, prompting the ECU to add fuel until the long-term trim hits the negative limit. Swapping sensors between banks is the fastest confirmation test.
How do I find Bank 2 on my V6 or V8?
Bank 2 is the side without cylinder 1. The numbering is documented in the workshop manual for each engine; do not assume your engine follows the most common pattern. Many BMW, Audi, and Mercedes engines have cylinder 1 on the passenger side, making Bank 2 the driver side, but exceptions exist.
