P0128 Code
A couple of times over the past few weeks my truck sets a P0128 code. It has always happened if I idle it a few minutes longer than normal before driving off such as when I'm hooking up my 5th wheel RV. This code is always followed by P0621.
Yesterday when the outside temp was in the low 50's I started it and drove off immediately, but slowly. After approx 1/2 mile and while doing 30-35 mph the code set again.
Am I looking at a bad thermostat that isn't staying closed long enough for the engine to heat up as fast as the computer thinks it should? I will admit this thermostat is original with 172,000 miles and 10 1/2 years service.
Thanks.
Ed
KM4STL
'06 Sierra LBZ 4x4 Crew SB, Titan 52 gallon fuel tank, TTT/Schefenacker Mirrors
'98 Suburban, 245,000 - sold 7-4-06