2010 Cadillac CTS Sedan AWD V6-3.0L Page 1904
enabled.
Conditions for Setting the DTC
P2177 or P2179
The Long Term Fuel Trim Cruise/Accel is greater than 32 % for 4 s or for a cumulative time of 30 s.
P2187 or P2189
The Long Term Fuel Trim Idle/Decel is greater than 6 % for 4 s or for a cumulative of 30 s.
Action Taken When the DTC Sets
DTCs P2177, P2179, P2187 and P2189 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2177, P2179, P2187 and P2189 are Type B DTCs.
Diagnostic Aids
* An HO2S will not cause this DTC to set without the occurrence of circuit related HO2S DTCs. Do not replace an HO2S to address this DTC.
* Observing the LT FT Bn 1 and Bn 2 parameters, while driving the vehicle can determine whether the lean condition is effecting only one
bank , or is common to both banks of the engine.
* A fuel system delivery condition causes this DTC to set. Thoroughly inspect all items that cause a lean condition. Refer to Fuel System
Diagnosis (See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Component Tests and General
Diagnostics/Fuel System Diagnosis).
* Any un-metered air into the engine causes this DTC to set. Thoroughly inspect all areas of the engine for vacuum leaks.
* A MAF sensor condition can cause this DTC without setting a MAF DTC. If there is a MAF sensor condition, the MAF sensor parameters
will appear to be within range.
* Inspect the air filter for being the correct one for this application. Make sure that the engine oil fill cap is in place and that it is tight. Verify
that the engine oil dip stick is fully seated.
Reference Information
Schematic Reference
Engine Controls Schematics (LLT) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)Engine Controls Schematics
(LF1) (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit Testing/Circuit Testing)
* Connector Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Connector Repairs/Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (See: Testing and Inspection/Component Tests and General Diagnostics/Circuit
Testing/Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/Wiring Repairs/Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (See: Diagnostic Trouble Code Descriptions/Powertrain Diagnostic Trouble Code
(DTC) Type Definitions)
Scan Tool Reference
Control Module References (See: Testing and Inspection/Programming and Relearning) for scan tool information
Circuit/System Verification
1. Observe the DTC information with a scan tool. DTC P2177, P2179, P2187, or P2189 should not be set.
瀚慖f any other DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (See: Diagnostic Trouble Code Descriptions/Diagnostic
Trouble Code (DTC) List - Vehicle) to diagnosis the applicable DTC.
2. Ignition ON, observe the barometric pressure (BARO) sensor pressure parameter and compare the reading on the scan tool to the barometric
pressure table. Refer to Altitude Versus Barometric Pressure (See: Powertrain Management/Computers and Control Systems/Specifications
