Lean Mixture
A lean mixture has more air than ideal for the amount of fuel.
What is Lean Mixture?
A little lean running is used for economy in some conditions, but too lean is harmful. Fault codes P0171 and P0174 report a lean mixture on bank 1 and bank 2. Positive fuel trims show the engine is adding fuel to correct a lean condition.
How it works
Extra air enters unmetered or too little fuel is delivered, so the oxygen sensor reads high oxygen.
Why it matters for your car
Lean running can cause hesitation, misfires and higher combustion temperatures. Vacuum leaks, a dirty MAF sensor and weak fuel pumps are common causes.
Other terms
- Airbag Replacement After Deployment
- Brake Vacuum Pump
- Car Loan
- Coachbuilder
- Degreaser (Engine Cleaner)
- Driving Range
- Dual-circuit Brakes (Split Brake System)
- Dynamic Load Management
- Heated Steering Wheel
- High-voltage Contactor (Main Relay)
- Ignition Timing
- Inertia Switch (Fuel Pump Cut-off Switch)
- Jockey Wheel
- Range Anxiety
- Sill Repair (Rocker Panel Repair)
- Spaceframe Chassis
- Spongy Brake Pedal (Soft Pedal)
- Third Brake Light (High-level Brake Light)
- Type Approval
- Wasted Spark Ignition