APP sensor? possible to be a problem without throwing code?
 

Have a problem in my 04 tl auto where it usually starts running like crap after 15 minutes or so. Sometimes it runs great, other times it feels like it's missing 100 horsepower. Is it possible to have a problem with the APP sensor and it not throw a code? I have no stored codes, but i've had this issue for quite a while now.

Yes-- there are at least a couple of APP (Accelerator Pedal Position) sensor threads where members had a bad APP sensor, but no codes-- a search should locate those threads.
Members seem to get a code when their TL stopped or wouldn't travel more than 30 mph due to a bad APP sensor.

G/L, and welcome to AZ.

Yes. Mine was giving a "bad throttle body" code. My mechanic put in 3 different throttle bodies before I found the APP suggestion here. He tested the sensor - it was bad.

Absolutely.

I thought that my tranny or TC (or both) was going out. Sluggish when driving, jerky to accelerate, hesitant sometimes at a stop. Turn out that 90% of it was the APP. The other 10% was a nearly impacted air filter that was full of those whilybird things from sliver maples trees that were wet and fermenting in there - I have no idea how the got in there (mouse?), but that is why we have filters.

Any sensor will put out a range of values... say from 5 to 100 for example. The car will not throw a code unless under 4, or over 101. However, it might not put out the right value for a given position. If 95 is WOT, then 40 will give you bad performance, but it is still in the range, so the car believes it is right. You can test resistance with the old vs. new with a DMM if you can figure out which wires a which... the APP was trickier than other sensors.

I've read so many APP thread issues on here over the years that the first time my engine starts acting like it's lost 1/2 its power, I'm replacing the APP sensor. Given the age of my '04 combined with the general APP sensor fail rate, I figure I'll have to replace it sooner or later anyhow. Might as well take a shot...

^ hesitation or holding gears for too long before shifts too.