- Vehicles
- Cars
Please check the OBC system
BYD 'Please check the OBC system' in car: on-board charger
Risk level
Medium
Proceed carefully and stop if the check is unclear.
Urgency
Medium
Quick answer
The prompt 'Please check the OBC system' on a BYD electric car points to a fault during AC charging. Unlock the charge port, inspect and reconnect the charging connector within 30 seconds, and contact a BYD authorized dealer or service provider if the message stays on.
Safety first
Stop and check this first
- Do not force the charging connector out while the charge port anti-theft lock is engaged, and never attempt to disassemble or repair the charging equipment or vehicle charge port yourself.
- Never charge if the port contains water or foreign objects, if metal terminals are rusty or corroded, or if the charging cable is soft, worn or cracked: short circuit or electric shock can cause personal injury.
Safe checks you can perform
- Unlock the port and reconnect the AC charging connector firmly
- Turn off scheduled charging when using third-party AC chargers
- Check the power supply indicator or test on another AC charger
Leave these tasks to a qualified professional
- Do not attempt this professional task: On-board charger (OBC) and charge port fault code diagnosis
- Do not attempt this professional task: OBC or charge port repair and verified AC charging test
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
On-board charger (OBC) and charge port fault code diagnosis
What they doThe BYD authorized service provider reads stored fault codes from the OBC module, inspects the charge port pins and locking mechanism, and checks the low-voltage battery state.
They must show youthe diagnostic scan report for the OBC module and the inspection result for the charge port terminals.
In writingall fault codes retrieved, the confirmed cause of the AC charging failure and the checks performed.
OBC or charge port repair and verified AC charging test
What they doThe technician repairs or replaces the faulty on-board charging component or port assembly and verifies normal AC charging operation.
They must show youthe vehicle charging on AC power with the green charging indicator active and the OBC prompt cleared.
In writingthe parts repaired or replaced and confirmation that AC charging completed a test session without fault prompts.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Unlock the port and reconnect the AC charging connector firmly
- Who:
- you, with the vehicle powered off and without forcing the anti-theft lock.
- How:
- press the smart key unlock button or door handle microswitch, pull the connector out within 30 seconds before the port relocks, verify the port and plug are dry and clean, and push the connector firmly back in.
- Result that matters:
- carrying out the immediate reconnection step that the BYD manual specifies for the OBC prompt.
- If the charge port light flashes green and charging starts:
- the connector had not seated properly.
- If the 'Please check the OBC system' prompt or solid red port light remains:
- check scheduled charging and the power supply.
- Evidence to keep:
- a photo of the instrument cluster prompt and the charge port indicator colour.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
Turn off scheduled charging when using third-party AC chargers
- Who:
- you, on the BYD infotainment touchscreen.
- How:
- open Energy > Charging Settings (or Charging and Discharging) and disable scheduled charging or switch to instant charging if you are plugged into non-BYD-certified slow AC equipment.
- Result that matters:
- ruling out a handshake failure between BYD's timer function and a third-party AC charger.
- If charging begins once switched to instant charging:
- keep scheduled charging disabled for that equipment.
- If instant charging still fails with the OBC prompt:
- check the outlet supply or try another charger.
- Evidence to keep:
- a photo of the Scheduled Charging setting screen on the infotainment display.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
Check the power supply indicator or test on another AC charger
- Who:
- you, looking at the charger status lights without opening outlets or panels.
- How:
- verify that the Mode 2 control box or AC charging pile power indicator is lit, make sure the cable is not coiled in a spiral, and test charging on another compliant AC outlet or station if available.
- Result that matters:
- telling a dead socket or faulty external charger apart from an on-board vehicle fault.
- If the car charges normally on another AC charger:
- have the original outlet or charging cable checked.
- If the OBC fault message appears on another AC charger too:
- stop charging and contact a BYD authorized dealer.
- Evidence to keep:
- a photo of the charger control box or station display where the fault occurred.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- BYD
- Product type
- Cars
Known code variants
- BYD charge port solid red light
- BYD charger connected but battery cannot be charged
- BYD el cargador está conectado pero la batería no se carga
- BYD fallo del sistema de carga integrado
- BYD luz del puerto de carga rojo sólido
- BYD OBC fault message
- BYD on-board charging system faulty
- Please check the OBC system
- Por favor, inspeccione el sistema OBC
What it means
In the BYD owner's manuals (ATTO 3 and NEW TANG), the instrument cluster prompt 'Please check the OBC system' warns that the on-board charging system is faulty, often paired with a solid red charge port light. BYD instructs you to check the charging connection and reconnect the charging equipment. The General Charging Troubleshooting table also notes that AC charging can fail or stop if the connector is loosely plugged in, the socket has no power, scheduled charging is used with non-BYD slow AC equipment, battery temperature is out of range, or the low-voltage battery is over-discharged. The prompt alone does not prove the OBC hardware has failed.
Warnings and stop conditions
- Mediumsource verified
Do not force the charging connector out while the charge port anti-theft lock is engaged, and never attempt to disassemble or repair the charging equipment or vehicle charge port yourself.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
- Highsource verified
Never charge if the port contains water or foreign objects, if metal terminals are rusty or corroded, or if the charging cable is soft, worn or cracked: short circuit or electric shock can cause personal injury.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
Symptoms and causes
Probable causes · in order
- Loose or partially inserted AC charging connectorCommon
BYD's first instruction for this prompt is to inspect and reconnect the plug because a loose AC connection prevents charging or interrupts it midway.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
- No power at the household socket or faulty AC charging pilePossible
The BYD charging troubleshooting table lists a power outage, tripped overload protection at the socket or a faulty AC charging station among causes of failed charging.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
- Scheduled charging enabled with non-BYD AC charging equipmentPossible
BYD cautions that scheduled charging is developed for BYD slow AC equipment only and may fail due to no response from third-party AC chargers.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
- Fault in the vehicle on-board charger (OBC) or charge port circuitPossible
If the plug and external supply are sound but the message persists after reconnecting, the vehicle's on-board charger or port electronics may have a fault.
Evidence: BYD ATTO 3 2025 owner's manual (left-hand drive) · BYD NEW TANG Manual del propietario (con volante a la izquierda)
Virtual technician
Does Please check the OBC system still appear after these checks?
Answer a few questions to narrow down the likely cause and the safest next action. Guidance only - it never replaces a professional.
Sources and technical references
- 1
BYD ATTO 3 2025 owner's manual (left-hand drive)
BYD Auto Co. Ltd. · 2025 · manual
- 2
BYD NEW TANG Manual del propietario (con volante a la izquierda)
BYD Auto Co. Ltd. · 2025 · manual
Was this entry useful?