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by Bob O’Neill and Bob Lincoln
Code 45 is used only on turbocharged engines — because it shows that the turbocharger boost (the amount of additional air pressure in the manifold caused by the turbocharger) is higher than the limit set by the ECU. When code 45 is set, the power limited light is not lit (it is lit as long as the overboost condition is experienced, but goes out once boost is seen as being in the acceptable range), and the system does not enter limp mode. Code 45 can be accompanied by code 36.
Poor wiring or connection - Read the page ‘How to troubleshoot drivability issues’. Check the wiring and connections from the logic module to the power module. Clean and re-grease the connectors with dielectric grease.
Bad vacuum line - Boost is controlled by a vacuum/boost line. If there is a faulty vacuum hose or connection the boost signal may not reach the wastegate solenoid properly. This may result in an overboost condition. Be sure to check all vacuum lines to insure there are no broken hoses/lines or connectors and that all hoses are connected properly. Also be sure to check the vacuum line to the MAP sensor. If any lines are bad, replace them.
Defective wastegate solenoid - The wastegate solenoid is located near one to three other solenoids. These are located on the right front fender. Review the ‘Understanding Solenoids’ page for additional information about solenoids.
Defective wastegate actuator spring – Inside the wastegate pod there is a spring. To check it, slide the wastegate actuator push rod into the actuator. It should be very hard to move. If it’s easy to move the spring inside the pod is broken and the wastegate should be replaced.
The wastegate rod connects with the wastegate on the swing valve. If the wastegate is jammed the actuator will not be able to move it. Disconnect the actuator rod from the wastegate at the swing valve and try to move the wastegate. The wastegate should have about 50 degrees of swing at the lever. If the lever moves easily the problem is with the wastegate pod and it should be replaced.
Code 45 trigger parameters – Overboost is reported as a function of the output of the MAP sensor. When the MAP sensor outputs exceed its cutoff point as sensed by the computer, code 45 is triggered. When overboost is detected the computer tries to limit the boost shutting down the injectors. When the computer senses that the has been reduced to between 3 and 5 psi the injectors are once again allowed to function and the power limited light is turned off. Overboost cut-off is based on the car, engine, year and transmission. A bad MAP sensor can cause an incorrect overboost reading.
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