P1491 — EGR Valve Insufficient Lift
CAUTIONIs it safe to drive? Drive gently and get it looked at soon — it can worsen or fail inspection.
What P1491 means
This is a manufacturer-specific code — its meaning depends on the vehicle’s make (see below).
What P1491 means on specific makes
Honda / Acura CAUTION
The EGR valve isn't opening (lifting) as much as commanded, usually from carbon buildup clogging the EGR ports. Very common on older Honda V6 (Accord/Odyssey/Pilot) and a frequent cause of stumble/surge.
- Carbon-clogged EGR ports in intake (clean, labor)
- Stuck/failed EGR valve ($80-200)
- EGR lift sensor fault
Check first: Remove and clean the EGR valve and intake EGR passages; clogged ports are the usual culprit on Hondas before condemning the valve.
Source: hondacodes.wordpress.com