Mitsubishi P1A99
ion battery starts to be charged. Balancer allowed to be driven is OFF. Either one of the following diagnostic trouble codes is not set . a. P1AA8: Bat-CAN signal tim
Quick answer
P1A99 is documented by Mitsubishi TSB-19-54-005 as a Battery Balancing Unit fault associated with CMU12 on the 2016 Mitsubishi i-MiEV (US).
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 P1A99 mean?
P1A99 is documented by Mitsubishi TSB-19-54-005 as a Battery Balancing Unit fault associated with CMU12 on the 2016 Mitsubishi i-MiEV (US).
2. Technical explanation
Verified evidence identifies P1A99 as “CMU12 Battery Balancing Unit.” The cited TSB lists trouble-judgment conditions including: three seconds after the electric motor switch is turned ON, or three seconds after main drive lithium-ion battery charging starts; balancer operation is not allowed; and a listed related DTC condition involving P1AA8 is referenced. The supplied excerpt is truncated and does not establish the complete diagnostic logic, root cause, or repair procedure.
3. What system is affected?
Main drive lithium-ion battery Battery Balancing Unit; specifically CMU12.
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
- A P1A99 diagnostic trouble code may be stored. Further vehicle symptoms are not yet established by verified evidence.
6. Possible causes
- The verified evidence identifies CMU12 Battery Balancing Unit in connection with P1A99. A specific failure cause is not yet established by verified evidence.
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
- Do not attempt high-voltage battery or Battery Balancing Unit repairs yourself.
- Arrange diagnosis by a qualified Mitsubishi EV service provider.
- Record any warning messages and whether the code occurred during vehicle start-up or charging.
10. Step-by-step troubleshooting
- Use appropriate manufacturer-level diagnostic equipment and the complete Mitsubishi service information to confirm P1A99 and inspect applicable related DTCs.
- The supplied TSB excerpt references P1AA8 in the trouble-judgment conditions.
- Further diagnostic steps are not yet established by verified evidence.
11. When to contact service
Contact a qualified Mitsubishi EV service provider for diagnosis, particularly because this code is associated with the main drive lithium-ion battery balancing system.
12. What the service center may check
- Confirm P1A99 and review stored diagnostic information using manufacturer-approved diagnostic equipment.
- Evaluate the Battery Balancing Unit/CMU12 according to the complete Mitsubishi service procedure.
- Review P1AA8 if present, because it is referenced in the verified TSB excerpt.
13. Possible repair or resolution
- Not yet established by verified evidence.
14. Affected vehicles
- Mitsubishi i-MiEV · 2016 · US
15. Related TSBs / service bulletins
- Mitsubishi TSB-19-54-005, published March 13, 2019, is the verified manufacturer communication that lists P1A99 as CMU12 Battery Balancing Unit.
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Verified source: NHTSA-hosted Mitsubishi manufacturer communication, TSB-19-54-005 (MC-10158410-9999): https://static.nhtsa.gov/odi/tsbs/2019/MC-10158410-9999.pdf
19. Frequently asked questions
What does P1A99 mean on a 2016 Mitsubishi i-MiEV?
The verified Mitsubishi TSB identifies P1A99 as CMU12 Battery Balancing Unit.
Which vehicle is covered by the supplied evidence?
The verified applicability evidence is for the 2016 Mitsubishi i-MiEV in the US.
Is P1AA8 related to P1A99?
The supplied TSB excerpt references P1AA8 in P1A99 trouble-judgment conditions. The exact relationship is not fully established by the supplied excerpt.
Can the vehicle be driven or charged with P1A99?
Not yet established by verified evidence.