BMW 21F116: High Voltage Battery Contactor Fault
BMW 21F116 means the SME battery management electronics sees the high voltage battery's negative contactor not closing as commanded, so the hybrid system never activates. On the affected PHEV production years the most common cause is a faulty safety box inside the high voltage battery, sometimes paired with an SME hardware mismatch, though on newer or out of range cars a genuinely stuck contactor has to be checked too.
Quick facts
- System
- Hybrid / High Voltage Battery
- Severity
- Serious
- Can you still drive?
- Short drives only, diagnose soon
- Applies to
- BMW SI B12 12 18 (April 2018) covers F15 PHEV (X5 xDrive40e), F30 PHEV (330e iPerformance), G12 PHEV (740e xDrive iPerformance) and G30 PHEV (530e iPerformance). The bulletin decision tree turns on vehicles built before 26 May 2017 and SME units built before 15 March 2017. The code is also reported by owners of the later G05 X5 45e.
Also shown by some scanners as: 21F1F8
Symptoms
- Powertrain malfunction message on the dash, check control message 633
- Engine fault, power loss message, check control message 29
- Hybrid system does not activate, so the car will not run on electric drive at all
- Charging fails or the car refuses to accept a charge
- Electric range shown as unavailable even after a full charge
Common causes, most likely first
- 1
Faulty safety box in the high voltage battery
The cause BMW names for the affected production period
- 2
Hardware version mismatch between the SME and the safety box
This makes the SME block activation of the high voltage system as a precaution
- 3
SME battery management electronics itself
BMW replaces this too depending on the production date of the car and the safety box
- 4
High voltage battery contactor genuinely stuck open
Has to be considered on cars outside the bulletin production range
- 5
Wiring and connector faults inside the high voltage battery unit
Usually found during the same inspection
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Frequently asked questions
Can I still drive with BMW code 21F116?
With the high voltage system blocked, the car loses electric drive and the dash reports a powertrain malfunction with power loss, so it will not perform as expected when pulling out. Keep any trip short and local until it is diagnosed. Never open or probe the high voltage battery yourself, this is workshop only work with the high voltage system properly de energised first.
Does 21F116 always mean the contactor is physically stuck or welded?
Not always. On the PHEV production years covered by BMW's bulletin, the code usually points to a faulty safety box or a hardware mismatch between the SME and the safety box, not a physically welded contactor. On a car outside that production range, a genuinely stuck contactor becomes a real possibility, so the exact cause needs a proper diagnostic read before any part is assumed to be at fault.
What does fixing 21F116 involve?
On the affected production years the fix usually centres on the safety box inside the high voltage battery, and sometimes the SME battery management electronics as well depending on the hardware versions involved, with programming carried out at the workshop afterwards. On other cars the workshop still needs to confirm whether the contactor, the SME, or wiring inside the battery unit is the actual cause before anything is opened. WhatsApp us the code and car model for stock and today's price.
Which BMW models does code 21F116 apply to?
BMW's bulletin covers the F15 PHEV (X5 xDrive40e), F30 PHEV (330e iPerformance), G12 PHEV (740e xDrive iPerformance) and G30 PHEV (530e iPerformance), specifically cars built before 26 May 2017 with an SME unit built before 15 March 2017. The later G05 X5 45e has also been reported with this code, but on that or any other car outside the bulletin's production range the cause needs its own fresh diagnosis rather than assuming the same fix applies.