Hello! Do you have a check engine light? I would recommend having your vehicle scanned to give you a better idea where to start diagnosis

Hi, I had this issue. It could be a sensor. Try the MAP sensor and secondary air injection too. That’s more inexpensive than changing the SAI hose.

Most likely you have a leak. Inexpensive enough to try but you should also check all plastic hoses top, back and front of 2.5L engine.

In my case, I didn't have an air leak and it was simply the sensor.

Hi Jeff, There might be some other issues besides the part you have replaced. For accurate diagnostic and repair, we recommend referring to a trusted vehicle specific repair manual for details about this particular problem you are encountering. Still, it is best to consult your trusted local auto repair shop or dealership for a certified mechanic to do an extensive careful troubleshooting and do the appropriate repair.

After I installed the secondary air injection sensor I used an obdeleven that I had purchased. Owning a Volkswagen this is a necessity. I am able to run Diagnostics on my car and clear codes Etc. Unfortunately with a Volkswagen most car parts place don't always have the equipment to evaluate the codes on a Volkswagen. I did not try any other means of erasing the code since I already owned the obdeleven. I hope this may help you.

Hi Bethany, thank you for reaching out. Yes, it will work for your Jetta. You can use the link below to order the part while it's on sale. Have a good one. https://www.carparts.com/secondary-air-injection-sensor/replacement/rv31520002?can=cpab2020

Hi Lance, Good Day! Thank you for your purchase. We sell Aftermarket products. Aftermarket products can be any part of a vehicle that is not sourced directly from the car's maker. These parts are direct replacement parts, designed to function the same, may not be physically identical to the original, but there are some instances that it even worked better than the OE parts. As to the P0491, here are some causes why the code pops out. Faulty exhaust manifold check valve. A fuse or relay for the secondary air injection pump may be faulty. A faulty air pump. Leaking vacuum hose. A bad vacuum control switch. A dislodged a vacuum line. A leak in the hoses/piping between the secondary air injection pump and the Combi or secondary air injection. A sensor for the secondary air pressure may be faulty. The combi valve itself is faulty The secondary air injection port in the cylinder head may be plugged with carbon. I highly suggest to do thorough check on the vehicle to check what cause the code to pop out. Hope this one helps.