Cruise Control Multi-Function Input "B" Circuit Range/Performance
The P0591 code means the vehicle's onboard diagnostic system has detected: Cruise Control Multi-Function Input "B" Circuit Range/Performance. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $50 - $400 (parts and labor)
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What Are the Symptoms of P0591?
- Check Engine Light on
- Cruise control will not engage or cancels on its own
- Vehicle otherwise drives normally
What Causes P0591? (Most Likely First)
- Worn or sticking cruise control switch High
- Damaged wiring or a faulty clock spring Moderate
- Corroded or loose connector Moderate
- Control module input fault Low
Can I Still Drive with P0591?
Yes, but fix soon. P0591 is rated low severity. It is not an immediate stop-driving fault, but it will not clear itself — book the repair rather than ignoring the light.
Frequently Asked Questions
What does P0591 mean?
P0591 means Cruise Control Multi-Function Input "B" Circuit Range/Performance. Cruise control switch input "B" is reporting values outside what the control module expects.
Can I still drive with this cruise control code?
Yes. It affects the cruise control, not how the vehicle drives. Fix it when convenient, and keep an eye on the Check Engine Light so it does not hide a new code.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose P0591?
-
Check which switch or input carries "B" on your vehicle in the service information.
-
Watch the cruise switch inputs on a scan tool while pressing each button.
-
Inspect the steering wheel switch connector and, if fitted, the clock spring wiring.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
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