P1085 on BMW
Fuel Control Mixture Lean, Bank 2 Sensor 1 (manufacturer-specific, common on BMW)
P1085 on BMW vehicles indicates fuel control mixture lean, bank 2 sensor 1 (manufacturer-specific, common on bmw). Au7o has documented this code across 1 BMW model — most commonly on M5. P1085 is a manufacturer-specific powertrain code, most commonly seen on BMW, indicating a lean fuel/air mixture on bank 2 of the engine as detected by the upstream oxygen sensor. The computer detected it was adding excessive fuel to correct for too much unmetered air, signaling a lean condition. It very commonly sets together with P1083 (the bank 1 equivalent), which usually points to an air leak affecting the whole engine rather than just one bank. Typical repair costs on BMW range from $300 to $900, depending on the specific model and root cause.
Common Causes of P1085
- •Vacuum or intake air leak after the MAF sensor
- •Failed crankcase ventilation (CCV) valve/hoses (BMW)
- •Dirty or failing mass airflow (MAF) sensor
- •Cracked or loose intake boot and manifold gaskets
- •Weak fuel pump or restricted fuel injectors
- •Faulty upstream oxygen (O2) sensor on bank 2
- •Leaking PCV or oil-cap/dipstick seals
P1085 on BMW by Model
BMW M5(1 issue)
- MAF Sensor Degradation Causing Lean Codes, Hesitation, and Reduced Power2000-2003
The S62 uses dual mass-airflow sensors, and aging or contaminated MAFs are a recurring E39 M5 issue. Owners commonly report rough idle, hesitation, poor throttle response, reduced power, and check-engine lights with mixture adaptation faults. BMW service literature and independent repair databases frequently reference diagnosis of intake leaks versus faulty MAF readings on E39 V8 applications.
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View P1085 across all makes →Frequently Asked Questions
What does P1085 mean on BMW?▼
P1085 stands for "Fuel Control Mixture Lean, Bank 2 Sensor 1 (manufacturer-specific, common on BMW)." P1085 is a manufacturer-specific powertrain code, most commonly seen on BMW, indicating a lean fuel/air mixture on bank 2 of the engine as detected by the upstream oxygen sensor. The computer detected it was adding excessive fuel to correct for too much unmetered air, signaling a lean condition. It very commonly sets together with P1083 (the bank 1 equivalent), which usually points to an air leak affecting the whole engine rather than just one bank. On BMW specifically, this code is documented across 1 model.
What causes P1085 on BMW vehicles?▼
Common causes on BMW: Vacuum or intake air leak after the MAF sensor, Failed crankcase ventilation (CCV) valve/hoses (BMW), Dirty or failing mass airflow (MAF) sensor, Cracked or loose intake boot and manifold gaskets, Weak fuel pump or restricted fuel injectors. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P1085 on a BMW?▼
Repair costs on BMW range from $300 to $900, depending on the specific model and root cause.
Which BMW models have P1085 documented?▼
Au7o has documented P1085 on 1 BMW model: M5.