ok, so i was on my way home from work the other day, and my check engine light came on, and then it went off after a little while...so i thought nothing of it. then the next day it came on 5 secs after startup, and stayed on all the way back to work, and the same on the way home....2 more days it did this (i was too busy to check the codes) so finally last night a pulled the KOER codes, and got 311(amongst others that always pop up) thermactor sytem fault.....ok....then today i started it up...check engine light...then drove a little ways....and off it went

now the question.......what parts in the thermactor system can temporarily fail? could this have anything to do with a certain 10 inch deep puddle i flew through a week ago? what things should i check?? and if this goes bad again will it cripple my truck??

 

Ok, there are a couple of checks to do first with a Thermactor code coming up. Check the plumbing. Start at the fresh air pump (smog pump) and work your way back to the diverter valve and finally down into the cat. air injection and the air injection crossover tub at the back of the cylinder heads. A series of formed rubber and steel hoses/tubes make up the Thermactor plumbing. Make certain you still have BOTH vacuum lines securely attached to the diverter valve. If they are, follow them back to the TAB and TAD solenoids and make sure everything (vacuum AND electrical) is still connected there as well.

Having the system inoperative won't necessarily do permanent damage but it will cause changes to O2 sensor readings and mess with your fuel/air ratio which translates to poor fuel mileage etc. All of the systems are so interconnected that one system pretty much affects the other sooner or later.

If there is nothing obviously wrong with any of the components mentioend above, make sure the pump is indeed doing its job and pumping fresh air. Make certain the intake hose for the pump is not blocked, crushed or clogged. Pull the output hose and start the truck. There should be significant air flow from the output hose barb on the pump. If the pump checks out the diverter valve is the next suspect. The only OTHER possibility involves a failed air control solenoid (TAB or TAD) which can be troubleshot but is a slightly tedious process. PM me if you think this is the problem and I can get you details.