'99 S70 Base 136K miles - P0172 Topic is solved

Post by **E Showell** » 16 Jun 2017, 03:19

Persistent P0172 code. Failed inspection. No vacuum leak at the small hose on the end of the intake manifold. Mechanic smoke tasted and says smoke pouring out of the area surrounding the idle air control valve. I've never had experience with an IAC valve failing. I guess they do. Sounds like it is time for a replacement.

Post by **abscate** » 16 Jun 2017, 05:12

E Showell wrote: ↑16 Jun 2017, 03:19 Persistent P0172 code. Failed inspection. No vacuum leak at the small hose on the end of the intake manifold. Mechanic smoke tasted and says smoke pouring out of the area surrounding the idle air control valve. I've never had experience with an IAC valve failing. I guess they do. Sounds like it is time for a replacement.

I'm in NJ tomorrow picking up family at EWR. Can give you an hour ?

Post by **E Showell** » 25 Jun 2017, 17:00

So, mechanic replaced Idle Control Valve with a new part. (Steve, the one you sent was bad as well). Check engine light in now extinguished. I continue to set the odd P1081 (immobilizer) code, however. More to the point and the reason for my post -- at about 50 mph on a downhill, and then later on level ground - coasting with foot off gas, idle speed did a gentle sweep from 1500 rpm up to about 1850, then back down, then back up, then back down. Sort of an oscillation. Mph did not change with idle speed, but remained rock steady at about 50 mph. Any ideas what this may be?

Post by **E Showell** » 13 Jul 2017, 19:38

Mechanic says idle sweep is ac compressor cycling. It was the idle control valve, not idle air control valve as previously stated. Nonetheless, the problem is solved.

Post by **abscate** » 14 Jul 2017, 03:45

Nice!!

Sorry for bad part hassle