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 has detected a problem with the sensor or switch that helps control how fast the engine runs when the car is not moving.
The P256D code is triggered when the Engine Control Module (ECM) detects a high voltage signal from the engine idle speed selector sensor or switch circuit.
The engine idle speed selector sensor or switch is responsible for providing the ECM with information about the desired idle speed. If the circuit provides a voltage reading that is higher than expected, the ECM will set the P256D code. This could be due to a short circuit, a faulty sensor, or an issue with the ECM itself.
• Check Engine Light is on
• Unstable or high idle speed
• Poor engine performance at idle
• Faulty engine idle speed selector sensor/switch
• Short circuit in the wiring
• Faulty ECM
ECM: Engine Control Module
OBD-II: On-Board Diagnostics II
• Use an OBD-II scanner to confirm the code.
• Visually inspect the wiring and connectors for damage.
• Test the sensor/switch voltage and resistance.
• Replace the faulty sensor/switch.
• Repair or replace damaged wiring.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Screwdriver set
$100 - $500
Moderate
• Vehicle 1
• Vehicle 2
• Vehicle 3
• Regular maintenance checks
• Ensure wiring is intact and free from corrosion
• Use quality replacement parts
Sensor Issue
• Avoid driving the vehicle until repaired.
• Consult a professional mechanic for accurate diagnosis.
Check with the vehicle manufacturer for warranty coverage on sensors and ECM.
This code has been known to appear in vehicles with electronic throttle control systems.
Moderate – It is advisable to address this issue soon to avoid potential drivability problems.
Ignoring this code may lead to increased emissions and potential safety risks.
• Engine at idle
• Vehicle in park or neutral
The engine idle speed selector sensor/switch is typically located near the throttle body or on the intake manifold.
Q: Can I drive with a P256D code?
A: It is not recommended to drive with this code as it may lead to unstable engine performance.
Q: How can I reset the P256D code?
A: After repairs, use an OBD-II scanner to clear the code from the ECM.
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