Engine-Codes - BMW - P1085 BMW

P1085 BMW Code - Fuel Control Mixture Lean Bank 2 Sensor 1

- Code Popularity: 43,741 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 2/3
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What are the Possible Causes of the DTC P1085 BMW?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Crankcase Ventilation Control Valve
  • Damage or loose Air Intake Tube
  • Faulty Mass Air Flow (MAF) sensor
  • Faulty Ignition Coil(s)
  • Faulty Spark Plugs
  • Insufficient fuel pressure
  • Large vacuum leak on the engine
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How to Fix the DTC P1085 BMW?

Check the 'Possible Causes' listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.

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What is the Cost to Diagnose the Code?

Labor: 1.0

The cost to diagnose the P1085 BMW code is 1.0 hour of labor. The diagnosis time and labor rates at auto repair shops vary depending on the location, make and model of the vehicle, and even the engine type. Most auto repair shops charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

What Does the P1085 BMW Code Mean?

To operate effectively, a gasoline engine requires a specific air-fuel ratio (lambda), with the theoretical ratio being 14.7:1. However, different operating conditions, such as temperature or acceleration, necessitate a deviation from this ideal ratio, requiring adjustments through various facilities.
For maximum power output, a rich mixture is necessary during full-throttle operation. If lambda is less than 1, there is insufficient air, and the fuel-air mixture becomes rich. On the other hand, if lambda is greater than 1, there is excess air, and the mixture becomes lean, reducing fuel consumption and power output.
However, if lambda exceeds 1.3, the air-fuel mixture becomes difficult to ignite, and the engine no longer operates within safe limits. In practical applications, a lambda value of 0.9 to 1.1 has proven to be most favorable. If the engine needs to operate at a lambda value of 1, a fuel injection system with emission control will be necessary to ensure proper mixture preparation.
The electronic fuel injection system measures the engine's air intake and converts it into an electrical signal for evaluation by the DME control unit. Based on this signal and other parameters, the control unit calculates the fuel requirement and activates electromagnetic fuel injectors. These injectors intermittently inject fuel ahead of the cylinder inlet valves.

P1085 BMW Code - Fuel Control Mixture Lean Bank 2 Sensor 1

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