Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means the car's computer thinks too much air is going into the engine because of what the oxygen sensor is saying. It's like the car is breathing too hard.
The OBD-II code P111A indicates that the oxygen sensor on Bank 1 is reporting a higher than expected air flow into the engine.
P111A is triggered when the Engine Control Module (ECM) detects a discrepancy between the expected air flow and the readings from the oxygen sensor on Bank 1. This suggests that the Mass Air Flow (MAF) sensor or oxygen sensor may be malfunctioning or that there is an air leak.
• Check Engine Light is on
• Poor fuel economy
• Rough idle
• Faulty Mass Air Flow (MAF) sensor
• Faulty oxygen sensor
• Vacuum leak in the intake manifold
MAF Sensor: Mass Air Flow Sensor, measures the amount of air entering the engine.
Oxygen Sensor: A sensor that measures the oxygen level in the exhaust gases.
• Use an OBD-II scanner to confirm the code.
• Inspect the MAF sensor and oxygen sensor for damage.
• Check for vacuum leaks in the intake system.
• Replace the faulty MAF sensor.
• Replace the faulty oxygen sensor.
• Repair any vacuum leaks.
• OBD-II scanner
• Multimeter
• Vacuum leak detector
$150 - $400
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly clean the MAF sensor.
• Perform routine maintenance on the intake system.
• Replace air filters as needed.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if you are unsure.
• Regular maintenance can prevent this issue.
Check with the vehicle manufacturer for specific warranty coverage on emissions-related components.
This code has been associated with issues in vehicles with high mileage or those that have not been maintained regularly.
Moderate – While the vehicle may still be drivable, it is important to address the issue to avoid further damage.
Driving with a malfunctioning sensor can lead to increased emissions and may not comply with local emissions regulations.
• Engine at operating temperature
• Vehicle at idle
The oxygen sensor is located on the exhaust manifold of Bank 1, while the MAF sensor is located in the intake air duct.
Q: Can I drive with a P111A code?
A: While you may be able to drive for a short period, it's best to fix the issue to avoid further engine problems.
Q: Will a P111A code affect my fuel economy?
A: Yes, a faulty sensor can lead to poor fuel economy due to incorrect air-fuel mixture.
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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.
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Fitment Required · Vehicle-fitment part
Relevant for airflow, fuel-trim, and intake-metering faults after confirming the sensor is actually at fault.
Airflow and fuel-trim codes can involve the mass air flow sensor after proper diagnosis.
Verify the sensor design and fitment for your exact vehicle.
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.