P256D Fault Code

Engine Idle Speed Selector Sensor/Switch Circuit High

• What does that mean?
• Symptoms
• Causes
• Solutions

The Engine Idle Speed Selector Sensor/Switch Circuit High fault code indicates an issue with the engine's idle speed control system. This code generally appears when the sensor or switch that regulates the idle speed detects a signal that is higher than the expected range. Proper idle speed is crucial for engine performance and smooth operation.

What are the symptoms of the P256D code?

Common symptoms associated with a high voltage reading on the idle speed sensor circuit may include:

• Erratic engine idle, with the engine revving too high or fluctuating
• Difficulty in maintaining a steady speed when idling
• Illumination of the check engine light on the dashboard
• Potential stalling when the vehicle is in gear

What causes the P256D code?

Possible causes of this fault code include:

• Faulty idle speed sensor or switch
• Wiring issues such as shorts or damage to the sensor circuit
• Poor ground connection for the sensor
• Malfunctioning engine control module (ECM) that misinterprets sensor signals
• Vacuum leaks that affect engine idle stability

How to fix P256D?

To resolve the Engine Idle Speed Selector Sensor/Switch Circuit High issue, consider the following troubleshooting steps:

• Inspect the sensor and its wiring for damage, and replace if necessary.
• Check electrical connections and ensure they are secure and free from corrosion.
• Test the idle speed sensor with a multimeter to ensure it meets the manufacturer's specifications.
• Clear the fault code after repairs and test drive the vehicle to see if the issue reoccurs.
• If the problem persists, further diagnostics may be required to check the engine control module and overall engine performance.