Servicing Infiniti Battery Voltage

This bulletin applies to 2015 Infiniti Q50 and Q60, 2015-2019 Q70, 2015-2017 QX50, 2015 QX60 and 2015-2017 QX70 vehicles equipped with multi-port injection. The MIL may be on, accompanied by DTC P0603 (ECM back-up circuit) set.

P0603 is often the result of low battery voltage, discharged battery or battery terminal disconnections.


1. Confirm battery voltage as described earlier and resolve any battery issues.

2. Connect the C-III plus VI to the vehicle.

3. Open C-III plus on the CONSULT PC.

4. Turn the ignition ON but do not start the engine.

5. Erase the DTC.

6. Turn the ignition off.

7. Turn the ignition on and wait for at least one second.

8. Turn the ignition off and wait for at least 10 seconds.

9. Repeat steps seven and eight 10 times.

10. Turn the ignition on. If P0603 is currently stored as a 1st trip DTC, refer to the ESM for further diagnosis. If DTC P0603 is not currently stored as a 1st trip DTC, the service procedure is complete.

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