Mass Air Flow Sensor Performance

Some 2019-2021 Silverado and Sierra models equipped with the 5.3L V8 engine (RPOs L82, L84) or 6.2L V8 engine (RPO L87) may have an illuminated Check Engine MIL and DTC P1682 (Ignition 1 Switch Circuit 2) set in the Engine Control Module (ECM) as an active or history code. DTCs P0101 (MAF Sensor Performance), P0689 (Engine Controls Ignition Relay Feedback Circuit Low Voltage). P16A7 (Engine Controls Ignition Relay Feedback Circuit 2) or P16BC (Engine Controls Ignition Relay Feedback Circuit 3) also may be set. In addition, the vehicle may have previously had the Mass Air Flow (MAF) sensor replaced due to DTC P0101. These conditions may be caused by a compromised connection within the Underhood Bussed Electrical Center (UBEC) connector X3 at position H6, which can result in DTCs P1682 and P0101 setting together.

Do not replace the MAF sensor if these DTCs are set. Inspect the wire-to-terminal connections inside the X3 connector at the UBEC assembly for signs of a marginal connection or loose wires, especially the duel crimp at location X3-H6. (Fig. 6)


Fig. 6


If the dual crimp wire has a poor connection (Fig. 7), repair the wire. Refer to Repairing Connector Terminals in the appropriate Service Information.


Fig. 7


If the dual crimp wire does not show any signs of a poor connection (Fig. 8) or if there is no trouble found with any wire-to-terminal connections, continue diagnosing the DTCs before replacing the MAF sensor.


Fig. 8


For additional information, refer to Bulletin #21-NA-032.


– Thanks to Dave MacGillis

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