code 17840 Secondary Air Injection Solenoid Valve car not idling well from cold

[rench]

got this code 17840 coming up, reset it but comes back. also when car is started from cold it doenst idle very well and seems to bog down unless you give it some revs. is this reltaed to this code and how can i fix this? cheers

[Dalo Harkin]

You can remove it, but depends on the car.

The SAI is used to warm the catalyst when the car is cold - if you have a sports cat/ de cat rip it out and put a resistor on the wire, depending on your airbox you will also need a blanking plug for that too.

[rench]

and what about fixing it? easy enough or cheap enough to do?

[Dalo Harkin]

You'll probably find that the pipes that go to/from the SAI are cracked they are the brittle black ones and they just crumble when you remove them, and when you call VW for replacement parts and tot it up, its more cost effective to remove the thing

Check for leaks in the pipes but be very careful because looking you may crack it more

[rench]

does this course rough idle from cold

[Dalo Harkin]

It can do yes