Hyundai engine RPM fluctuation
Some 2009 Hyundai Veracruz, Santa Fe, Azera, Entourage and Sonata vehicles equipped with 2.7, 3.3 or 3.8L engines may experience either slight engine RPM fluctuation during initial warm-up, or an illuminated MIL (malfunction indicator lamp) that indicates a problem with the ETC (electronic throttle control system). This may include DTC P2135 (throttle position sensor ½ voltage correlation) and DTC P0638 (throttle actuator control range/performance).
This incident may be accompanied by other DTCs since the vehicle may have incurred operation at limited power, such as DTC P1295 (ETC system malfunction/forced limited power) and DTC P2106 (ETC system malfunction (power management).
The repair action includes replacement of the TPS (throttle position sensor), and performing the ECM software update/reflash.