Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer thinks there's too much air and not enough fuel in one part of the engine when the car is not idling.
The engine control module (ECM) detects that the air-fuel mixture is too lean (too much air, not enough fuel) in Bank 2 when the engine is off idle.
The P21F6 code is triggered when the ECM identifies a lean condition in the fuel control system for Bank 2. This occurs when the oxygen sensors detect a higher than expected amount of oxygen in the exhaust, indicating an imbalance in the air-fuel mixture.
• Check Engine Light is on
• Poor engine performance
• Rough idle
• Vacuum leaks
• Faulty oxygen sensor
• Fuel injector issues
Lean Condition: A condition where there is too much air and not enough fuel in the air-fuel mixture.
Oxygen Sensor: A sensor that measures the amount of oxygen in the exhaust gases.
• Use an OBD-II scanner to confirm the code.
• Inspect for vacuum leaks in the intake system.
• Check the oxygen sensors for proper operation.
• Repair any vacuum leaks found.
• Replace faulty oxygen sensors.
• Clean or replace fuel injectors if necessary.
• OBD-II scanner
• Vacuum gauge
• Multimeter
$150 - $500
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regular maintenance of the fuel system
• Checking for vacuum leaks periodically
• Ensuring oxygen sensors are functioning correctly
Engine Performance
• Do not ignore the Check Engine Light.
• Get the vehicle diagnosed as soon as possible to avoid further damage.
Check if the vehicle's emissions warranty covers oxygen sensors and related components.
This code has been associated with vehicles that have experienced vacuum leaks or faulty oxygen sensors.
Moderate – Should be addressed soon to prevent potential engine damage.
Driving with a lean condition can lead to increased emissions and potential engine damage.
• Engine running off idle
• Warm engine temperature
Bank 2 refers to the side of the engine opposite cylinder 1, typically on V-type engines.
Q: What does 'Bank 2' mean?
A: Bank 2 refers to the side of the engine opposite cylinder 1, often found in V6 or V8 engines.
Q: Can I drive with a P21F6 code?
A: It's not recommended to drive for extended periods with this code, as it can lead to engine damage.
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Fitment Required · Vehicle-fitment part
Relevant when the code or supporting diagnostics point toward upstream or downstream oxygen-sensor faults.
This code family often involves upstream or downstream oxygen-sensor diagnosis.
Verify exact sensor position and vehicle fitment before buying.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.