So my truck has always had an intermittent problem with throwing code p1291, especially when its wet out (rare these days in California).  PO told me when I bought it that if I ever had the CEL come on it was almost certainly a loose post connection sleeve at the relay (skinny wire press on sleeve) working loose.  Ive generally found that to be the case, but im getting tired of it happening and am wanting to fix it for good.  Ive already tried to pinch them slightly for better connectivity with limited success.  Any issue with clipping them off and replacing with ring terminals to screw down?  Anyone know the size off hand?

http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes-cummins/212-p1291-no-temperature-rise-seen-from-intake-heaters

Start here with the link above and do what you can of the diagnostic.

Edited November 21, 20159 yr by Mopar1973Man