Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2008CHEVY EXPRESS G2500, VAN CARGO, 6.6 6REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1801 (ENGINE CONTROLS AND FUEL - 4.4L - DTC P0010 TO DTC P0158)DTC P012BCIRCUIT/SYSTEM VERIFICATION
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6
Circuit/System Verification
2008 Chevrolet Chevy Express G2500, Van Cargo, 6.6 6SECTION Circuit/System Verification
WARNING: This page is about a different car, the 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
- Verify DTCs P0102, P0103, P0106, P0107, P0108, P0121, P0641, P0651, P2228, or P2229 are not set.
- If the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Ignition ON, observe the MAP and SC Inlet Pressure Sensor kPa parameters with a scan tool. Start the engine and let it idle. The MAP Sensor and SC Inlet Pressure Sensor kPa parameters should decrease and closely match each other.
- If the MAP Sensor parameter does not decrease and closely match the SC Inlet parameter, refer to DTC P0106 .
- Ignition ON, depress the accelerator pedal completely to wide open throttle (WOT) and observe the TP Indicated Angle parameter with a scan tool. The TP Indicated Angle parameter should read 98-100 percent.
- If the TP Indicated Angle parameter is not within the specified range, refer to DTC P1516, P2101, P2119, or P2176 .
- Ignition ON, perform a snapshot of the throttle actuator control (TAC) data while performing the following actions. Refer to Scan Tool Snapshot Procedure
.
- Slowly depress the accelerator pedal to WOT and then slowly release the pedal. Exit from the snapshot and review the data.
- Compare the TP Sensor 1 and the TP Sensor 2 parameters, frame by frame. The difference between the parameters should be less than 4 percent.
- If the difference is greater than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 .
- Road test the vehicle and perform a brief wide open throttle (WOT) acceleration from 30 mph. The MAP sensor parameter on the scan tool should increase rapidly. This increase should be from approximately 35 kPa at idle to greater than 135 kPa.
- If less than the specified range, refer to Boost Control System Diagnosis .
- A skewed or stuck ECT, BARO, MAP, MAF/IAT, or IAT sensor 2 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistance and Altitude Versus Barometric Pressure .
- Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.