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Mitsubishi P1A9A

CMU ID auto numbering error . TROUBLE JUDGMENT Check Conditions  When the CMUs are numbered for identification.  Either one of the following diagnostic trouble codes is not sto r

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceContact a Mitsubishi dealer or qualified EV service provider for BMU and main drive lithium-ion battery diagnosis.
Confidence95%

Quick answer

P1A9A is a Mitsubishi Battery Management Unit (BMU) diagnostic trouble code for a CMU ID auto-numbering error. Verified information identifies invalid CMU identification-number information as the judgment criterion.

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 P1A9A mean?

P1A9A is a Mitsubishi Battery Management Unit (BMU) diagnostic trouble code for a CMU ID auto-numbering error. Verified information identifies invalid CMU identification-number information as the judgment criterion.

2. Technical explanation

The published Mitsubishi diagnostic material describes P1A9A as “CMU ID auto numbering error.” Its check condition is when CMUs are numbered for identification. The judgment criterion is that information pertaining to the identification number is invalid. The source also references U1925, “CMU ID numbering reception error,” in the diagnostic context.

3. What system is affected?

Battery Management Unit (BMU) and main drive lithium-ion battery system. CMU is referenced by the verified diagnostic material, but its expanded name is not established by the supplied evidence.

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

  • Invalid information pertaining to a CMU identification number is the verified judgment criterion.
  • Any further underlying 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

  • Have the vehicle evaluated using the specified Mitsubishi diagnostic process.
  • Do not attempt high-voltage battery or BMU repair without qualified EV service training and equipment.

10. Step-by-step troubleshooting

  1. The published procedure includes checking whether the diagnostic trouble code is stored using scan tool MB991958.
  2. In the cited procedure, if the diagnostic trouble code is stored, the instruction is to replace the BMU.
  3. In the cited procedure, if the diagnostic trouble code is not stored, the check is complete.

11. When to contact service

Contact a Mitsubishi dealer or qualified EV service provider for BMU and main drive lithium-ion battery diagnosis.

12. What the service center may check

  • Use scan tool MB991958 to determine whether the diagnostic trouble code is stored.
  • Follow the applicable Mitsubishi published diagnostic procedure for the vehicle.

13. Possible repair or resolution

  • The cited Mitsubishi procedure directs BMU replacement when the diagnostic trouble code is stored.
  • No other repair resolution is established by the supplied evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • TSB-19-54-003, published March 13, 2019; NHTSA manufacturer communication MC-10158408.
  • TSB-19-54-004, published March 13, 2019; NHTSA manufacturer communication MC-10158409.

16. Recall information

No recall relationship is established by verified evidence.

17. Official manufacturer information

Verified official NHTSA-hosted Mitsubishi manufacturer communications: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158408-9999.pdf and https://static.nhtsa.gov/odi/tsbs/2019/MC-10158409-9999.pdf

19. Frequently asked questions

What does Mitsubishi code P1A9A mean?

It means “CMU ID auto numbering error,” according to the verified Mitsubishi diagnostic material.

What does the diagnostic judgment criterion state?

The criterion states that information pertaining to the identification number is invalid.

What does the published procedure instruct if P1A9A is stored?

The cited procedure instructs replacement of the BMU.

Which vehicles are established as applicable by the supplied evidence?

US-market 2012 and 2014 Mitsubishi i-MiEV vehicles.

20. Sources & verification

Verified
Mitsubishi P1A9A: CMU ID auto numbering error . TROUBLE JUDGMENT Check… | EV Diagnostics