I'm curious if a ticking valve can trip the code 52. I also want to know what the code 52 limp mode is like. I have a code 52 truck seems to run fine. I drive it daily and do 65 on the fwy. I have a ticking valve and I'm wondering if I have been driving it daily in limp mode.

 

No.

Code 52 does not mean "your engine is knocking." It means "gosh, I can't tell, I haven't heard from the knock sensor. To avoid damaging the engine (since I don't know how close the engine is to knocking) I'll retard the timing a lot."

"But this isn't a secret; I'll tell the driver by setting code 52."

Retarded timing can be masked by other things (like having the base timing way advanced). I'd expect it to take a while to get up to 65mph with severely retarded timing.