Reference meaning
What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Narrow by vehicle
A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Scan worksheet →Manufacturer wording
Source wording can vary by vehicle and suffix. It is shown as written, not as a universal diagnosis.
P1491VACUUM CUT VALVE BYPASS VALVE
Manufacturer communications
12Original wording in English
HONDA
HONDA SERVICE CAMPAIGN: SEE DOCUMENT SEARCH BUTTON FOR OWNER LETTER. WARRANTY EXTENSION: EGR VALVE CONTAMINATION OR EGR PORT CLOGGING MAY CAUSE DTC P0401, DTC P1491, OR ENGINE HESITATION/SURGE. CSC WAS RECEIVED. *NJ
ACURA
ACURA SERVICE CAMPAIGN: SEE DOCUMENT SEARCH BUTTON FOR OWNER LETTER. WARRANTY EXTENSION: EGR VALVE CONTAMINATION MAY CAUSE ENGINE HESITATION/SURGE OR DTC P1491. CSC WAS RECEIVED. *NJ
HONDA
WARRANTY EXTENSION: EGR VALVE CONTAMINATION OR EGR POR CLOGGING MAY CAUSE DTC P0401, DTC P1491, OR ENGINE HESITATION/SURGE. *TT
HONDA
REQUEST FOR VISIT. CUSTOMER COMPLAINT OF THE ENGINE STUMBLING, SHUDDERING, HESITATING, OR MOMENTARILY SURGING. MAY ALSO EXPERIENCE A CHECK ENGINE LIGHT, AND DIAGNOSTIC TROUBLE CODE (DTC) P1491 MAY BE DISPLAYED. *TT
Check vehicle applicability
23A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
Code meaning and manufacturer information
Original wording in English · Historical directory labels; manufacturer applicability has not been established for every entry.
Secondary Switch Solenoid Circuit Malfunction
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.