Check engine light popped on yesterday. Code reader says; PO491- Secondary Air Injection System bank 2. Anyone here have an idea of what might have triggered this, and what component to look at?

thanks.
John

 

For diagnosing the cause for DTC P0491 to trigger the MIL, you may find this helpful:

https://www.troublecodes.net/pcodes/p0491/

 

Thanks NBCat.

im trying to learn what components make up the “ secondary air injection system”. Couldn’t find that on the link.

 

I’ve deleted the CEL, and in a short 30 mile run, it hasn’t come back.

 

Most codes need 2+ warm ups to flag.

 

by “ flag”, do you mean that the code is erased? Or?

 

John,

I ran a global search for P0491 in the XK Workshop Manual and this code is not defined for the X150 although it was used by Jaguar for earlier models. What combination of diagnostics tool and DTC lookup did you use to return this code and decode? My guess is it wasn't SDD ......

Graham

 

I went to a local parts house, Advanced Auto, and they plugged their code reader into the OBDII port.. it reads:

”PO491- Secondary Air Injection System ( bank 2)”

 

 

The DTC is P0491, not PO491.

Not sure about the accuracy of that paper as it also shows the vehicle mileage as 6069038.

 

There is no doubt you had a code that triggered the MIL but I question the compatabilty of their code reader with the X150 and consequently the accuracy of the reported code. Clearing codes is the nuclear option for turning off the MIL. If it doesn't come back on (normally after 2 "trips" if the underlying fault has not been rectified) then no need to be concerned. If it does come on, you need to consider a Jaguar diagnostics (SDD) session or re-check with a known compatible reader.

Graham

 

Graham,

ive driven the car about 6 times since clearing the code. 15-25 miles each. Nothing came back.....yet.

thanks for your input.

John

 

Dollars to Donuts it's a vacuum leak. Maybe do a smoke-check.

 

is this something I can perform, or do I need to take it to the dealer?

 

Most small Indie shops can do a check for like $50. A dealer would probably charge $250 or more.
You CAN do it yourself, but you would first need to get yourself a smoke machine for like $200.

 

Thanks Cee Jay.