QuestionI am seeing the following errors . . . and roughly when they show after cleaning the codes from my reader (I try to check codes after every 25 miles of driving!):
P1471 - As soon as the engine starts
P1472 - Not always -- but showed up recently (came after driving 25 miles)
P0171 - Comes after ~50-100 miles of driving
P0174 - Typically comes after 1~50-200 miles of driving . . . sometimes goes off on its own
SES light comes on when P0174 shows. It goes off when P0174 goes away. P0171 does no go off on its own.
Dealer said vacuum leak in PCV, MAF and VIS motors problem. I asked him to replace the PCV hose. I also changed the MAF last week. After changing MAF I am still seeing P1471, P1472 and P1071 (SES light has not come on yet).
I also changed VIS motor #2 last winter (at that time I started getting P1471 instead of P1472). So I am not sure whether the motors are really bad or they are getting incorrect signals (from wherever they get the signal).
I have changed spark plugs on the front bank (I guess LH), but have not been able to do it on the rear bank because of the difficulty in accessing.
What can be the problem? Can O2 sensor on Bank1 malfunction cause problems in Bank2 and hence SES light? Or changing spark plugs on one bank only can cause such a problem? Or there can be more vacuum leaks or low fuel pressure? Can VIS motors cause a lean A/F mix as seen by P0171 and P0174?
I am at loss now because I can not keep on changing parts unnecessarily. The vehicle is running fine in general . . . except minor hesitation while changing gears (it's automatic). I am due for an emission inspection in a month ; so would like to clean up this error if possible.
AnswerThe VIS codes will not pull up a check engine light. It is quite common for these cars to have stored VIS codes like this. It is unlikely that the VIS motors would cause the engine to run lean.
P0171 and P0174 are normally air leaks or an air flow meter. It is certainly possible that you could have more air leaks. Make sure the O2 sensors are swinging and there are no air leaks. If all else fails, change the whole inlet manifold. These are a major problem on these cars. I would try to find a good used one.
