I have a 2001 VW Jetta GL, manual transmission, with 62,000 miles on it (bought new in California in November 2000). It seems like every time I go on a long road trip, the check engine light comes on. My longer trips generally involve a change in altitude (e.g. from sea level to going over a mountain) or changes in temperature (e.g. sun to snow, or mild to very hot). The issue with the check engine light has come up at least three times, and the culprit is always some sort of sensor. I've replaced two oxygen sensors, a coolant sensor, and most recently a mass air sensor (finally -- one that was still covered under warranty). None of these issues has ever caused a problem with the car's drivability, but it seems like I should be able to change altitude/temperature without blowing a sensor! Am I alone in this, or is this a common Volkswagen glitch?
Has anyone had problems with their VW Jetta when changing altitude or temperature?
I think it is just a coinky dink that these sensors have failed with changes in altitude. A closed loop fuel injection system is designed to adapt to altitude changes by monitoring atmospheric pressure via the map sensor or baro sensor. Most engines these days have done away with the baro sensor, and just use the key on, engine off map sensor as the baro reading at startup. With the key on engine off, the map sensor is reading no vacuum or pressure which equals atmosperic pressure. When I was first taught engine control systems, I learned that one way to real time adapt the engine to atmosheric pressure changes is to press the gas pedal to the floor after you have changed altitudes. Again, when you do this, engine vacuum goes to zero at WOT, and will register the updated atmospheric pressure with out shutting the engine off and turning the key back on.
I really cannot see the correlation between altitude changes and a sensor failing. I work in engine management systems testing and development, and this has never come up before.
I'll be sure to ask around, but I think I know what everyone's response will be.
Has anyone had problems with their VW Jetta when changing altitude or temperature?
my VW Van was the most temperamental vehicle I've ever had! VW's simply have a mind of their own
