would a stuck open thermostat trigger the check engine light?

[alimo20]

i'm pretty sure my thermostat is to blame for the very long warm-up period. i did a coolant flush and something must have screwed the coolant system. was wondering if a check engine light would come on for a stuck open thermostat..

[B72.0T]

Or maybe it's just the really cold weather we've been having...

[alimo20]

it started 3 weeks ago, when it was much nicer out..

[Charles.waite]

No it wont. My B7's thermostat is stuck open and no MIL. Doesn't even throw a code.

[pondside36]

Yes it will, mine was bad and when I removed it I noticed it was broken and stuck open. The CEL associated with it was for cooling system. This also caused slow warm up and never truly warmed and stayed at mid position on the temp gauge. When it was colder than 40 degrees it would also stall out from time to time in the first 10 minutes of driving when I came to a complete stop or shifted from neutral to 1st gear.

[Charles.waite]

Oh really? weird. Mine doesn;t even throw a code. I know its bad though. Strange...

[pondside36]

The CEL was associated with the difference in coolant temps at cold idle and running, not an actual CEL for just the T-stat. Changed sensors first which left only the T-stat. Yours maybe partially stuck, mine was 100% wide open.

[Charles.waite]

The CEL was associated with the difference in coolant temps at cold idle and running, not an actual CEL for just the T-stat. Changed sensors first which left only the T-stat. Yours maybe partially stuck, mine was 100% wide open.

I actually don't know. When I logged measuring block 130 and 131, the only reading it spit out was the Engine temp. Everything else was blank, including the Thermostat duty cycle, which shows the opening percentage of the T-stat.