Fault Code 45


Notes:  For Turbo models only

Description:  Turbo boost limit exceeded
Power loss light:  On
Limp-in mode:  None

Possible Causes

Vaccum leak - Check all vaccum lines between the wastegate actuator, manifold, and wastegate solenoid.  Also check the line to the MAP sensor.  Repair or replace any bad lines.

Wastegate solenoid failure - The wastegate solenoid is located in the right, front fender next to one to three other solenoids.  See the Understanding Solenoids page.

Bad connection or wiring - Check the wiring and connections between the logic modle (or SMEC) and the wastegate solenoid.  Clean and regrease any corroded connectors with dielectric grease and repair any shorts. This condition may be accompanied by a code 36.

Wastegate actuator spring failure - Try to slide the wastegate to wastegate actuator push rod into the actuator.  It should not move.  Try to pull it out.  If it pulls out with little effort (even if it springs back in), replace the actuator.

Jammed wastegate - Disconnect the wastegate actuator pushrod and swing the wastegate arm on top of the turbo.  It should have about a 50 degree swing.  Make sure the lever and push rod are clear of any obsticles that may cause them to jam (the heat shield below the fuel rail is a major culprit).

Diagnostic Method

Trigger Parameters

- MAP sensor output voltage has exceeded overboost cut-off point
Overboost Cut-off Points by Year, Engine, and Transmission
Year Engine Manual Auto
1984 Turbo I 4.30V 4.30V
1985 Turbo I 4.54V 4.65V
1986 Turbo I 4.65V 4.88V
1987 Turbo I 4.65V 4.88V
1987 Turbo II 4.65V ?

Following years are probably the same as 1987, but I don't have any hard data to back that up. Some have said that 4.74V was the max for Turbo I engines of later years. Some information indicates that the Turbo II with an automatic had a cut-off of 4.96V, but I don't know of any Turbo II vehicle that had an automatic transmission.

Results If Component Fails

A fault code 45 is stored, the power loss light is turned on, and the fuel injectors are shut off. Once the boost has fallen to 3 psi to 5 psi, the fuel injectors are turned back on and the power loss light is turned off. The overboost cut-off point for a particular vehicle depends on the year, engine, and transmission.
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This page is maintained by Russell W. Knize and was last updated 08/28/98. Comments? Questions? Send email.

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