Cause
Faulty on-board charger
The unit that converts alternating current from a domestic or public supply into the direct current a traction battery can accept has failed.
Its scope is narrower than people assume, and knowing the boundary saves a great deal of misdiagnosis. It handles AC charging only — a home socket, a wallbox, a street post. Rapid DC charging bypasses it entirely, because the charge point does the conversion itself and feeds the pack directly.
Which gives the single most useful diagnostic in the whole charging system, and it costs nothing: try both kinds. A car that rapid-charges perfectly and refuses every AC supply has a fault in the on-board charger or its path. A car that fails on both has a fault somewhere they share — the inlet, the contactors, the pack, or the control electronics. One test, and the problem is halved.
The unit is liquid-cooled on most vehicles and works hard for hours at a time, so its failures are often thermal: reduced charging rate before outright failure, worse in summer, worse again if the electronics coolant circuit is low or airlocked. A charger that has become slow rather than dead is worth investigating as a cooling fault before it is condemned.
It is rarely a serviceable item — usually a sealed assembly, sometimes integrated with the DC/DC converter into one unit, which is worth establishing before comparing quotes because it changes what is actually being replaced.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
1 of the 110 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (110)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0CF8 Control Pilot Charging Switch A Circuit/Open Likely for this code High
- P0CF9 Control Pilot Charging Switch A Range/Performance Likely for this code Moderate
- P0CFA Control Pilot Charging Switch A Circuit Low Likely for this code Moderate
- P0CFB Control Pilot Charging Switch A Circuit High Likely for this code Moderate
- P0CFC Control Pilot Charging Switch A Intermittent/Erratic Likely for this code Moderate
- P0CFD Control Pilot Charging Switch A Stuck Off Likely for this code High
- P0CFE Control Pilot Charging Switch A Stuck On Likely for this code High
- P0D20 Battery Charger A Output Voltage Performance Likely for this code High
- P0D21 Battery Charger A Output Voltage Too Low Likely for this code High
- P0D22 Battery Charger A Output Current Performance Likely for this code High
- P0D23 Battery Charger A Output Shorted Likely for this code Stop driving Critical
- P0D26 Battery Charger System Precharge Time Too Long Likely for this code High
- P0D2A Battery Charger Input Current Too High Likely for this code High
- P0D38 Battery Charger A Input Current Sensor Circuit Likely for this code High
- P0D39 Battery Charger A Input Current Sensor Circuit Range/Performance Likely for this code High
- P0D3A Battery Charger A Input Current Sensor Circuit Low Likely for this code High
- P0D3B Battery Charger A Input Current Sensor Circuit High Likely for this code High
- P0D3C Battery Charger A Input Current Sensor Circuit Intermittent/Erratic Likely for this code High
- P0D3D Battery Charger A Input Voltage Sensor A Circuit Likely for this code High
- P0D3E Battery Charger A Input Voltage Sensor A Circuit Range/Performance Likely for this code High
- P0D3F Battery Charger A Input Voltage Sensor A Circuit Low Likely for this code High
- P0D40 Battery Charger A Input Voltage Sensor A Circuit High Likely for this code High
- P0D41 Battery Charger A Input Voltage Sensor A Circuit Intermittent/Erratic Likely for this code High
- P0D42 Battery Charger 14 Volt Output Voltage Sensor Circuit Likely for this code High
- P0D43 Battery Charger 14 Volt Output Voltage Sensor Circuit Range/Performance Likely for this code High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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