Hyundai P1B25
Hybrid Battery Safety Plug Or Fuse Circuit NOTE: This bulletin does not apply for just a DTC P1B77 or P1B25, it must also have P1BA7. This bulletin’s Service Procedure will convert
Quick answer
For applicable 2016–2017 Hyundai Sonata vehicles in the US, P1B25 is identified as “Hybrid Battery Safety Plug Or Fuse Circuit.” The verified Hyundai bulletin applies only when P1BA7 is also stored; P1B25 alone is not covered by that bulletin.
This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.
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1. What does P1B25 mean?
For applicable 2016–2017 Hyundai Sonata vehicles in the US, P1B25 is identified as “Hybrid Battery Safety Plug Or Fuse Circuit.” The verified Hyundai bulletin applies only when P1BA7 is also stored; P1B25 alone is not covered by that bulletin.
2. Technical explanation
The verified manufacturer communication states that P1B25 may be stored in the Battery Management System (BMS) together with P1BA7, “Overcharge Detection Active.” P1B77, “High Voltage Battery Precharging Fault,” may also be present. When P1BA7 is present with P1B25 and/or P1B77, the bulletin’s procedure converts the PHEV battery overcharge-detection system from a mechanical Voltage Protection Device (VPD) switch to an electronic Overvoltage Protection Device (OPD) internal to new SUB BMS and MAIN BMS units.
3. What system is affected?
Hybrid battery/Battery Management System (BMS); the bulletin specifically concerns the PHEV battery overcharge-detection system.
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
Not yet established by verified evidence.
6. Possible causes
- The verified bulletin identifies P1B25 as a Hybrid Battery Safety Plug Or Fuse Circuit DTC. It does not establish a specific root cause for P1B25.
- For the bulletin procedure, P1B25 must be accompanied by P1BA7, Overcharge Detection Active.
7. Can I still drive the vehicle?
Not yet established by verified evidence.
8. Can I charge the vehicle?
Not yet established by verified evidence.
9. What you can safely do
- Have the vehicle evaluated by a Hyundai dealer or qualified service facility.
- Record all stored DTCs, including whether P1BA7 and P1B77 are present with P1B25.
- Do not assume the cited bulletin applies when P1B25 is the only stored code.
10. Step-by-step troubleshooting
- Verify whether the vehicle is a US-market 2016–2017 Hyundai Sonata.
- Retrieve BMS DTCs and confirm whether P1BA7 is stored with P1B25.
- If P1BA7 is present, check the applicable Hyundai service information and manufacturer communication 10127010 for the specified service procedure.
- Not yet established by verified evidence: additional diagnostic steps, circuit tests, or component-level repair steps.
11. When to contact service
Contact a Hyundai dealer or qualified service facility, especially if P1BA7 is stored together with P1B25.
12. What the service center may check
- Confirm BMS DTC P1BA7, Overcharge Detection Active, is present with P1B25.
- Check whether P1B77, High Voltage Battery Precharging Fault, is also stored.
- Confirm vehicle applicability before using the bulletin procedure.
13. Possible repair or resolution
- When the bulletin criteria are met, the verified communication states that its procedure converts the PHEV battery overcharge-detection system from a mechanical VPD switch to an electronic OPD internal to new SUB BMS and MAIN BMS units.
- The exact repair steps are not established by the supplied evidence.
14. Affected vehicles
- Hyundai Sonata · 2016–2017 · US
15. Related TSBs / service bulletins
- NHTSA Manufacturer Communication PDF 10127010, document 5NP-X4Q7Y-01; published December 21, 2017. It applies only where P1BA7 is present along with P1B25 and/or P1B77. Source: https://static.nhtsa.gov/odi/tsbs/2017/MC-10127010-9999.pdf
16. Recall information
No recall relationship is established by verified evidence.
17. Official manufacturer information
Verified source: NHTSA-hosted Hyundai manufacturer communication 10127010 (5NP-X4Q7Y-01), published December 21, 2017: https://static.nhtsa.gov/odi/tsbs/2017/MC-10127010-9999.pdf
19. Frequently asked questions
Does the cited Hyundai bulletin apply to P1B25 by itself?
No. The verified bulletin explicitly states that it does not apply for P1B25 alone; P1BA7 must also be present.
What is P1BA7 in the verified bulletin?
P1BA7 is identified as “Overcharge Detection Active.”
Can P1B77 be present with P1BA7?
Yes. The bulletin states that P1B77 and/or P1B25 may be stored along with P1BA7.
Which vehicles are established as applicable by the supplied evidence?
US-market 2016–2017 Hyundai Sonata vehicles.