Case Study
Range Rover Sport Charge Fault
Our customer brought in their 2021 Range Rover Sport with a charge fault warning message on the dashboard. A charging fault can quickly leave you with a flat battery and a car that won't start, so our technicians carried out a thorough diagnostic investigation to find the cause before it left our customer stranded.
Fault Codes
P065B-16 – Generator control circuit range/performance – circuit voltage below threshold
Common Symptoms
- Charge fault warning message on the dashboard
- 12V battery not charging
- Low battery state of charge
- Starting problems or start/stop not working
Range Rover Sport Diagnostics
We confirmed the charge fault was present when the vehicle came into the workshop. A fault code scan of the gateway module returned P065B-16, Generator control circuit range/performance, circuit voltage below threshold, and the serial data confirmed the 12V battery was not being charged. A visual inspection showed no obvious faults or damage, and there were no relevant technical bulletins, which is common with DC-DC converter faults. On this Range Rover Sport, the 12V battery is charged from the hybrid system through a DC-DC converter rather than a conventional alternator, and our dealer-level diagnostic equipment has a dedicated test for it. Because the original 12V battery's state of charge had dropped to 48%, we temporarily fitted a donor battery so we could run the test accurately. The DC-DC converter failed the test, pointing to an internal failure of the converter, so we refitted the customer's original battery ready for the repair.
Vehicles Affected
Range Rover Sport
- Range Rover Sport 2018
- Range Rover Sport 2019
- Range Rover Sport 2020
- Range Rover Sport 2021
- Range Rover Sport 2022
Range Rover
- Range Rover 2018
- Range Rover 2019
- Range Rover 2020
- Range Rover 2021
- Range Rover 2022
Land Rover Discovery
- Land Rover Discovery 2021
- Land Rover Discovery 2022
- Land Rover Discovery 2023
- Land Rover Discovery 2024
DC-DC Converter Replacement
With the cause confirmed, we gained access to the DC-DC converter, fitted a new unit and reassembled the vehicle. As the fault had left the 12V battery undercharged, we deep charged it for several hours and retested it. The battery tester measured 623A against the battery's 850A rating and recommended a replacement, although the state of charge and state of health readings were both good. We cleared all fault codes, started the vehicle and checked the charge rate, which confirmed the 12V battery was now being charged.
Resolution
We road tested the vehicle locally and it drove well, with the 12V battery charging correctly and the start/stop system working again. Because the battery tested below its rated output, we advised our customer to keep an eye out for any starting issues, as the 12V battery may need replacing in the future. With the charge fault fixed, our customer's Range Rover Sport was safe and back on the road.
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Excellent customer service. Both Kev and Stacey were very helpful in a Stressful situation! Great company to deal with. Thank you!
Amie
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