Fuel Injector Driver DTCs Diagnostic Tip

If fuel injector driver DTCs are found on some 2019 Silverado 4500 MD, 5500 MD, 6500 MD models equipped with the 6.6L Duramax diesel engine (RPO L5D), it may be due to switching the transfer case into 4WD and driving the vehicle without locking the front hubs. (Fig. 17)


Fig. 17


The following injection timing DTCs may be set: P01CB,  P01CC,  P01CD,  P01CE, P01CF,  P01D0,  P01D1,  P01D2,  P01D3,  P01D4,  P01D5,  P01D6,  P01D7,  P01D8,  P01D9, and P01DA. The ECM adjusts the injection timing for each fuel injector based on the changes in the rotational speed of the crankshaft. The DTCs will set if the fuel injection quantity or timing are out of range.

If there is more than one Small Quantity Adjustment (SQA) DTC set, or any combination of codes set, ask the customer if there was a chance that the vehicle was driven with the four-wheel drive transfer case knob in the 4WD position, but the front hubs were not locked.

If the transfer case knob (located near the exterior lamps knob on the left side of the instrument panel) (Fig. 18) is placed in 4WD and the vehicle is driven without locking the front hubs, these codes may set. If the vehicle has been driven under these circumstances, clear the DTCs and advise the customer of proper 4WD operation.


Fig. 18


– Thanks to Richard Renshaw

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