Boost pressure governing is used to control an exhaust turbocharger with the waste gate as well as a turbocharger with variable geometry turbocharger (VGT) For governing a VGT the actuator is the variable turbine geometry. The boost pressure is subdivided into recognition of driving style, stepoint value calculation, boost pressure governor (closed-loop control), boost pressure open-loop control, controlled adaption of governor parameter and monitoring, and shut-off. The absolute or relative boost pressure is calculated from a stepoint value map depending on engine speed and fuel quantity.
If an unusually low or high air pressure is being read by the VGT system, or there are air pressure readings that do not correspond to the expected engine load (too high or too low) during two driving cycles, these codes will be set.
If the VGT actuator electrical circuit is short to ground or open circuit during two driving cycles, this code will be set.
DTC NO.
Detecting Condition
Possible Cause
C 018
C 019
C 029
? C 018
Short circuit to battery line
? C 019
Open circuit :
? Short circuit to ground
? Wire broken
? Too high temperature in power stage
? C 029
Error is recognized if |actual boost pressure - target boost pressure| is above ± 500 hPa when the engine speed is above 1500 rpm and the fuel quantity is above 40 cc
? Engine Condition : RUN
? Fuel Limit : NO
? Fuel Cut : NO
? EGR OFF : NO
? MIL : NO
? LIMP HOME MODE
VGT vaccum actuator is fixed the duty ratio of 31.4 %
? Open or short in circuit
? VGT SOL. VALVE
? AFS
? ECM