TOPIC: TPMS light is as bad as a CEL

I've recently discovered that cars with Tire Pressure Monitoring System (TPMS) affect the fuel map ECUs use in fuel delivery.
If you get that warning light on your instrument cluster, until it's been reset, your vehicle is in "limp home" mode, just like a Check Engine Light. So keep those tires filled!

Again, Thanks Dr Dude!!

Thats good to know, I never knew that. I wonder what sensitivity range these TPMS systems have, like how low the tires have to get to trigger this light? As well- how about inflating higher than "spec"? It would be annoying to set the light off if tires were, say, 4 or 6 lbs higher pressure than spec. Going further- what if a different set of tires is fitted with a different pressure range or spec? Like I found out a while back, when I got new tires for the Subie, I'd had several sets on both it and a previous daily driver, and all were rated for 44 lbs max pressure. The latest set is rated at 51 lbs. I keep 'em at 55 psi cold.

see where I'm going here? But in any case, this is good info, thanks to Dr. Dude!

Tracy G
Gadgetman Reno Nevada

Well, I can tell you that on the vehicle in question, the light gets triggered when the pressure dropped 8psi from where I had the tires set. That's about 15%.
As far as tolerance, I'd venture a guess that +/- 15% is in the safe range before the system gets triggered.
Now...I would also guess that anytime the system is reset after being triggered is the baseline the system uses.
Just guessing, but a 30% range around the tire ratings seems fair, allowing for weight and heat and barometric factors.
I'm sure if somebody dug into the interweb researching this they will get a bunch of answers in the neighbourhood of what I've just surmised.