What are the common causes of P056B?

A failed adaptive cruise control sensor. A camera or radar unit that dropped out. Damaged sensor wiring. A PCM software fault. A bad vehicle speed sensor.

Read adaptive cruise sensor data on a scan tool. Inspect the sensor and camera for damage or obstruction. Check the sensor wiring for damage. Verify the vehicle speed sensor signal. Replace the sensor if it will not respond. Clear the code and retest.

P056B

Cruise Control Decrease Distance Signal

System: Speed and idle control (P code)
Lamp: Check Engine Light
Category: Powertrain - Computer and Auxiliary Controls

What it means

P056B means Cruise Control Decrease Distance Signal.

Check these first

A failed adaptive cruise control sensor
A camera or radar unit that dropped out
Damaged sensor wiring
A PCM software fault
A bad vehicle speed sensor

What to do next

Read adaptive cruise sensor data on a scan tool
Inspect the sensor and camera for damage or obstruction
Check the sensor wiring for damage
Verify the vehicle speed sensor signal
Replace the sensor if it will not respond
Clear the code and retest

Look up another code

Code or symptom

Enter a full code or a symptom. Press / to search. How to read a code

Type a code above, or start from a symptom or a common code.

Updated

Generic SAE J2012 definition. Last updated 2026-10-10.