For no apparent reason my ECM warning light came on this morning. Drove about 50 miles and everything seems normal. My truck is an 04.5 with 54,000 miles. The codes it shows are P191 and P0088. We are supposed to leave friday pulling our 11,000 # fifth wheel some 800 miles and I am concerned.

Any suggestions would be appreciated.

Cigar Mike

 

I'm not sure what an ECM light is. Are you referring to the Check Engine Light (CEL)? If so, on my 06 it has came on a few times and will automatically reset itself after about 10 start stop cycles if the condition that caused the CEL is not repeated. I am not sure if this is true of the 04.5 as well.

 

https://www.dieseltruckresource.com/...n&onlynewfaq=1
there's the code list from the dtr tech facts section.

your codes are rail pressure related. what fueling mods do you have?