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 is trying too hard to adjust the fuel mix for one side of the engine. It's like if you keep adding more sugar to your lemonade because it tastes too sour, but it never seems to get sweet enough.
The engine control module (ECM) is compensating too much to maintain the correct air-fuel ratio by adjusting the fuel trim on Bank 1.
P1159 indicates that the fuel trim adaptation value for Bank 1 has exceeded its upper limit. This suggests that the ECM is adding more fuel than usual to maintain the optimal air-fuel mixture. This can be due to a variety of reasons, such as a vacuum leak, faulty sensor readings, or fuel delivery issues.
• Check Engine Light is on
• Poor fuel economy
• Rough idle
• Vacuum leak
• Faulty mass airflow sensor
• Fuel injector issues
ECM: Engine Control Module, the computer that controls engine management.
Fuel Trim: Adjustments made by the ECM to the amount of fuel injected into the engine.
• Use an OBD-II scanner to confirm the code.
• Inspect for vacuum leaks in the intake system.
• Check the mass airflow sensor for proper operation.
• Repair any vacuum leaks.
• Clean or replace the mass airflow sensor.
• Inspect and clean fuel injectors.
• OBD-II scanner
• Vacuum gauge
• Multimeter
$100 - $500
Moderate
• Honda Accord
• BMW 3 Series
• Toyota Camry
• Regular maintenance checks
• Timely replacement of air filters
• Use quality fuel
Engine Performance
• Have your vehicle inspected by a professional if you notice the check engine light.
• Regularly check and maintain your vehicle's air intake system.
Check with your vehicle manufacturer; emissions-related components may be covered under warranty.
This code has been commonly associated with air intake system issues and is often resolved by addressing vacuum leaks or sensor faults.
Moderate – It should be addressed soon to prevent potential engine damage or poor performance.
Driving with a check engine light on can lead to further damage and may not pass emissions tests.
• Engine at operating temperature
• Vehicle idling
Bank 1 refers to the side of the engine with cylinder 1, typically located on the driver's side in a V-type engine.
Q: Can I drive my car with a P1159 code?
A: It's possible to drive, but it's not recommended for long periods as it can lead to further engine issues.
Q: How can I prevent a P1159 code from occurring?
A: Regular maintenance, including checking for vacuum leaks and ensuring sensors are clean and functioning, can help prevent this code.
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