Brake Switch "A" Circuit
The DURAMAX-P0571 (Duramax) diesel fault code means: Brake Switch "A" Circuit. This is a moderate severity code.
- Keep driving?
- Yes, with caution
- DIY difficulty
- intermediate
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What Are the Symptoms of DURAMAX-P0571?
- Check Engine Light on
- Cruise control may not engage or may cancel
- Brake lights may not work correctly
What Causes DURAMAX-P0571? (Most Likely First)
- Misadjusted or failed brake switch High
- Damaged wiring or a corroded connector at the switch Moderate
- Blown fuse Low
Can I Still Drive with DURAMAX-P0571?
Yes, with caution. DURAMAX-P0571 is rated moderate severity. Keep trips short and get it diagnosed soon rather than waiting for symptoms to worsen.
Frequently Asked Questions
What does P0571 mean on a Duramax?
P0571 means Brake Switch "A" Circuit. The control module has detected a fault in the brake switch "A" circuit.
Is P0571 a Duramax-specific code?
No. P0571 is a generic OBD-II code defined by SAE J2012, so it means the same thing on any vehicle that sets it. The exact conditions GM uses to set it on its diesels are in GM service information.
Mechanics Guide Step-by-step diagnosis
How Do You Diagnose DURAMAX-P0571?
Check that the brake lights work.
Watch the brake switch input on a scan tool while pressing the pedal.
Check the switch adjustment and wiring.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines P0571 as a generic OBD-II code)
P0571 on Other Platforms
The same code ID appears across other engines, vehicles, and equipment. Diagnostic flow varies by platform — see the matching breakdown:
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