P1406 - FAULT CODE - OBD2

P1406 BUICK, CADILLAC, CHEVROLET, GMC: EGR VALVE PINTLE POSITION CIRCUIT

The EGR (Exhaust Gas Recirculation) valve has a sensor that detects the position of the EGR valve shaft and then transmits that data to the Powertrain Control Module (PCM). The EGR position changes according to signal voltages ranging from 0.1 to 0.3. The PCM memorizes the valve signal voltage when the valve is closed after a vehicle activation. This value is used by the PCM as a reference and is compared to subsequent values of the closed position during each ignition activation.

The PCM often checks the EGR shaft position to verify that the EGR shaft position is within the parameters necessary for the best performance. If the EGR shaft position is +10% of the expected position, the P1406 OBD2 diagnostic code will be set.

• Check Engine light ON.
• Starting the engine is hard.
• The engine power is reduced.
• Irregularities in idling.
• Unexpected engine stalling.
• Engine knocking during engine load increases.

Reasons why the OBDII DTC P1406 is set:

• The EGR shaft circuit may be faulty in its wiring or connectors.
• The Exhaust Gas Recirculation Valve may be in poor condition.
• Any moving parts in the EGR valve may have excessive levels of wear.

To troubleshoot the P1406 OBD2 fault code you must do the following:

• First, consult the TSBs.
• With the ignition switch on, use a scan tool to determine what position the EGR shaft is in. Then, refer to the vehicle's data source and check what voltage should be present. If you notice a different voltage than specified, check for blockages preventing the valve from closing. Correct if necessary.
• Check for damage to the EGR valve shaft circuit wiring and connectors. If you discover common deficiencies, make repairs.
• With the EGR connector disconnected, check if the EGR signal voltage is 0. If the result is higher than this, measure the reference voltage, resistance, signal ground, and continuity to verify that an open or shorted circuit does not exist. Repair if necessary
• Check the Exhaust Gas Recirculation Valve for blockages or obstructions that may prevent it from working properly. If there is wear in any of its parts, replace it.