GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 STS 🢒 DTC 🢒 DTC P029D, P02A1, P02A5, P02A9, P02AD, or P02B1

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P029D: Injector 1 Leak

DTC P02A1: Injector 2 Leak

DTC P02A5: Injector 3 Leak

DTC P02A9: Injector 4 Leak

DTC P02AD: Injector 5 Leak

DTC P02B1: Injector 6 Leak

Circuit/System Description

The fuel injectors are mounted in the cylinder head beneath the intake ports and spray fuel directly into the combustion chamber. Direct injection requires high fuel pressure due to the fuel injector's location in the combustion chamber. High pressure fuel is regulated by the fuel rail pressure (FRP) regulator, which is a part of the high pressure fuel pump. The engine control module (ECM) monitors the actual fuel rail fuel pressure via the FRP sensor and commands the FRP regulator duty cycle in order to maintain the desired fuel rail pressure. If a fuel injector delivers more fuel than is needed misfire counts will accumulate on that cylinder, and the ECM will not be able to maintain the desired fuel rail pressure, indicating a stuck open or leaking fuel injector.

Conditions for Running the DTC
    • The engine speed is between 1,520-6,000 RPM
    • The engine load is less than 100 percent.
    • The misfire monitor is enabled.
    • DTC P029D, P02A1, P02A5, P02A9, P02AD, and P02B1 run continuously once the conditions above have been met for approximately 20 seconds.

Conditions for Setting the DTC

The ECM detects a specific cylinder misfire rate of greater than 100 counts in less than 17 engine revolutions, and P0087 is set. The condition exists for greater than 4 seconds or for a cumulative of 30 seconds.

Action Taken When the DTC Sets
    • DTCs P029D, P02A1, P02A5, P02A9, P02AD, and P02B1 are Type A DTCs.
    • The control module commands the engine to operate in the Reduced Engine Power mode.
    • The message center displays Reduced Engine Power.

Conditions for Clearing the DTC

DTCs P029D, P02A1, P02A5, P02A9, P02AD, and P02B1 are Type A DTCs.

Diagnostic Aids

A fuel injector leak into the combustion chamber may result in mechanical damage to the cylinder.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Verification
  1. Clear the DTC information with a scan tool.
  2. Engine operating, raise the engine speed to 2,000 RPM. Observe the DTC information with a scan tool. DTC P029D, P02A1, P02A5, P02A9, P02AD, or P02B1 should not set.
    3. ⇒If a DTC failed this ignition, replace the appropriate fuel injector.
  3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Injector Replacement