Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with the part of the car that helps control how fast the engine runs when the car is just sitting still.
The P256A code is triggered when the engine control module (ECM) detects an issue with the circuit of the engine idle speed selector sensor or switch.
The engine idle speed selector sensor or switch is responsible for communicating the desired idle speed to the ECM. If the circuit is open or there is a malfunction, the ECM cannot properly control the engine idle speed, leading to this trouble code.
• Engine idles erratically
• Check engine light is on
• Poor engine performance at idle
• Faulty idle speed selector sensor/switch
• Open or shorted wiring in the circuit
• Poor electrical connection at the sensor/switch
ECM: Engine Control Module
OBD-II: On-Board Diagnostics, Second Generation
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the idle speed selector sensor/switch for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the idle speed selector sensor/switch if faulty.
• Clear the code and test drive the vehicle to ensure the issue is resolved.
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $300
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect and maintain vehicle wiring.
• Ensure connectors are clean and secure.
• Perform routine vehicle diagnostics.
Sensor Issue
• Do not ignore the check engine light.
• Have the vehicle inspected by a professional if unsure.
• Avoid driving with erratic idle to prevent further damage.
Check with the vehicle manufacturer for warranty coverage on sensors.
This code has been associated with idle control issues in various vehicles, often due to sensor wear or wiring problems.
Moderate – While the vehicle may still be drivable, it should be repaired soon to prevent further issues.
Driving with a malfunctioning idle control system can lead to safety issues and increased emissions.
• Engine at operating temperature
• Vehicle in park or neutral
The idle speed selector sensor/switch is typically located on the throttle body or intake manifold.
Q: Can I drive with a P256A code?
A: It's possible to drive, but it's not recommended as it can lead to further issues.
Q: How do I clear a P256A code?
A: After repairs, use an OBD-II scanner to clear the code, then test drive to ensure it's resolved.
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