P1491 Infiniti Code - Vacuum Cut Valve Bypass Valve
Quick Answer
The vacuum cut valve and vacuum cut valve bypass valve are installed in parallel on the EVAP purge line between the fuel tank and the EVAP canister. Common causes include Vacuum cut valve bypass valve, Vacuum cut valve, Bypass hoses for clogging. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P1491 Infiniti indicates Vacuum Cut Valve Bypass Valve.
- Common causes
- Common causes include Vacuum cut valve bypass valve, Vacuum cut valve, Bypass hoses for clogging.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P1491 Infiniti Description
The vacuum cut valve prevents the intake manifold vacuum from being applied to the fuel tank. The vacuum cut valve bypass valve is a solenoid type valve and generally remains closed. It opens only for on board diagnosis.
The vacuum cut valve bypass valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the valve is opened. The vacuum cut valve is then bypassed to apply intake manifold vacuum to the fuel tank.
What are the Possible Causes of the DTC P1491 Infiniti?
- Vacuum cut valve bypass valve
- Vacuum cut valve
- Bypass hoses for clogging
- EVAP control system pressure sensor and circuit
- EVAP canister vent control valve
- Hose between fuel tank and vacuum cut valve clogged
- Hose between vacuum cut valve and EVAP canister clogged
- EVAP purge port of fuel tank for clogging
How to Fix the DTC P1491 Infiniti?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P1491 Infiniti code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P1491 Infiniti code?
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Frequently Asked Questions about P1491 Infiniti Code
No Frequently Asked Questions about P1491 Infiniti Code found.
Discuss the causes and fixes for P1491 Infiniti OBDII Code
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2001 Infiniti Qx4 (4wd) Code P1491 Engine Light ON going to fix it Thank you.
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Diagnosing the P1491 is a bit difficult, but most of the times the problem is the Vacuum cut valve bypass valve.
The valve is on the back of your QX4, underneath. Here is the only image I got.
Click here to enlarge image -
Am looking for this vacuum cut valve bypass valve. Is there a site where I can find this part .
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You need the location of the valve or a website to buy the part? what model and year is your vehicle?
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Original error code was P1492, Vacuum Cut Valve Bypass Valve. Replaced the Vacuum Cut Valve and Caniste . Drove it abt 30 miles and check engine light back on. Now error code is P1491, same parts. Any suggestions?
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