P0401Mclaren P1Years: 1996 - 2026
Exhaust Gas Recirculation (EGR) Flow Insufficient Detected
Reviewed by ASE Certified Technician
What does this mean?
Code P0401 indicates that the EGR system flow is less than expected. The EGR valve may not be opening enough or EGR passages are clogged.
Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Mclaren P1 models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.
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Common Causes
Stuck or faulty EGR valve
Clogged EGR passages
Vacuum leak in intake system
Damaged, chafed, or broken wiring harness
Symptoms to Watch For
- Check Engine Light is illuminated
- Engine knocking or detonation noise
- Failed emissions test
- Engine pinging under load