Check engine light flashes when coasting downhill.

[Neitron]

I have a 2013 PIU, I replaced the trans last summer and have had a problem when drive higher speeds. If I am going 75-80 and the road start heading down hill. If I let off the gas completely to not accelerate any more, The check engine light will start flashing and when I step on the gas, the engine acts weird. It starts running like it's skipping cylinders and shifts 'down'. After a few seconds of driving like this, the trans shifts and the engine runs smoothly. The check engine light stays on but there is no warnings.

 

[410Fortune]

if the CEL is on there is a code in memory
It maybe a transmission slipping code which requires a scanner that can receive manufacture specific codes
They are not designed to coast.................

 

[peterk9]

As mentioned above, check for any stored trouble codes. I believe that a flashing warning light is a sign of more serious issues than a steady on light.

Peter