Pontiac Repair: 2007 pontiac montana sv6, pontiac montana sv6, pontiac montana

Question
QUESTION: the engine lite keeps coming on even after I changed 4 different parts for emission code P0455,any help would be appreciated

ANSWER: Hi Elliot:

that code can be any # of things from a gas cap loose to a vent valve on the tank that is bad. The system needs to be properly looked at with a diagnostic tool called a smoke machine in conjunction with a scan tool. guess iat what part it could be is just that. Basically that code sets when the evap system wants to capture the vapor in the tank and the canister for reburning in the engine and the engine computer doesn't see it happening so it turns the lamp on. with out either tools your just guessing and wasting money. take it to a reputable repair shop or the dealer to get it looked at properly. The smoke machine will presurize the system with compressed nitrogen and a smoke and any leak in the system the smoke will leak out and that is where the issue is then. good luck :)


---------- FOLLOW-UP ----------

QUESTION: further help required. The tranny gives a hard clunk when starting to drive from stop sign or traffic light. Dealer 5 times replaced a few parts with no good results. The GM dealer would not replace tranny and now it is out of warranty and stll the same problem exists. Any ideas?

Answer
does the trnamission slip then grab and bang into gear or is it just a clunk you feel? It may not be a tranmsssion issue. It could be a motor mount or something in the suspension. That is an odd thing for this powertrain in that van. They usually do not have issues like that. Gm has a policy that they will not replace transmission just because. there is a cost analysyis that goes on if the price of the parts that went bad plus the labor are less then a replacement the original one gets fixed. It's not the delaers fualy it comes from above.