OBD2 Car ScannerWhat does P0594 mean?
P0594 stands for Cruise Control Servo Control Circuit/Open. The engine computer has found a problem with vehicle speed signals, idle control or another sensor input.
Powertrain codes cover the engine, transmission and emissions. When the car's computer sees a reading outside its normal range, it stores this code and may turn on a warning light on the dashboard.
Common causes
- Faulty vehicle speed sensor
- Dirty throttle body or idle air control valve
- Faulty switch or sensor
- Damaged wiring or connector
What to do
- Read all stored and pending codes with a scanner. Several codes together often point to one cause.
- Note the freeze frame data (speed, temperature, load) recorded when the code was set.
- Inspect the wiring and connectors of the part named in the code for damage, corrosion or looseness.
- Fix the most likely and cheapest cause first, then clear the code and drive to see if it comes back.
Read this code from your own car
Plug in a cheap ELM327 adapter and the app shows every fault code, what it means and how to fix it.
Frequently asked questions
What does P0594 mean?
P0594 means “Cruise Control Servo Control Circuit/Open”. It belongs to the speed, idle control and inputs group: The engine computer has found a problem with vehicle speed signals, idle control or another sensor input.
Is it safe to drive with P0594?
You can usually drive carefully for a short time, but fix it soon to avoid further damage or higher fuel use.
How do I clear P0594?
Fix the cause, then clear the code with an OBD2 scanner or app. If the fault is still there, the code will come back.
Related codes
- P0590Cruise Control Multi-Function Input B Circuit Stuck
- P0591Cruise Control Multi-Function Input B Circuit Range/Performance
- P0592Cruise Control Multi-Function Input B Circuit Low
- P0593Cruise Control Multi-Function Input B Circuit High
- P0595Cruise Control Servo Control Circuit Low
- P0596Cruise Control Servo Control Circuit High
- P0597Thermostat Heater Control Circuit/Open
- P0598Thermostat Heater Control Circuit Low
Code meanings can vary by manufacturer. This page is general guidance, not a repair manual. Always confirm the cause before replacing parts.