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Mitsubishi P1A90

CMU03 balancer abnormal, P1A91: CMU04 balancer abnormal, P1A92: CMU05 balancer abnormal, P1A93: CMU06 balancer abnormal, P1A94: CMU07 balancer abnormal, P1A95: CMU08 balancer abnor

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceService evaluation is appropriate because the documented procedure can require Main Drive Lithium-ion Battery or BMU replacement. The supplied evidence does not establish urgency, drivability, or charging restrictions.
Confidence95%

Quick answer

P1A90 is identified in Mitsubishi service bulletin evidence as “CMU03 balancer abnormal.” It applies to U.S.-market 2012 and 2014 Mitsubishi i-MiEV vehicles in the supplied data. The bulletin’s diagnostic path calls for battery-sensor checks, then replacement of the Main Drive Lithium-ion Battery if those checks are not normal; if checks are normal and the DTC remains stored, it calls for BMU replacement.

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 P1A90 mean?

P1A90 is identified in Mitsubishi service bulletin evidence as “CMU03 balancer abnormal.” It applies to U.S.-market 2012 and 2014 Mitsubishi i-MiEV vehicles in the supplied data. The bulletin’s diagnostic path calls for battery-sensor checks, then replacement of the Main Drive Lithium-ion Battery if those checks are not normal; if checks are normal and the DTC remains stored, it calls for BMU replacement.

2. Technical explanation

The verified Mitsubishi bulletin evidence identifies P1A90 as a CMU03 balancer abnormal condition. CMU03 is one member of a group of CMU balancer DTCs listed in the bulletin, from P1A8E through P1A99. The supplied bulletin excerpt describes a diagnostic sequence using scan tool MB991958. It directs the technician to evaluate battery sensor 1–6 checks. If the check result is not normal, the bulletin directs replacement of the Main Drive Lithium-ion Battery, followed by the next diagnostic step. If the checks are normal, the technician checks whether the DTC is stored. If it is stored, the bulletin directs replacement of the BMU; if it is not stored, the check is complete. The supplied evidence does not establish the exact underlying component-level failure mechanism, driver-visible behavior, or charging and driving restrictions.

3. What system is affected?

Main Drive Lithium-ion Battery, battery monitoring system (BMU), and CMU03 balancing function.

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

  • A non-normal battery sensor 1–6 check result is addressed by the bulletin through replacement of the Main Drive Lithium-ion Battery.
  • A stored P1A90 after normal battery sensor 1–6 check results is addressed by the bulletin through replacement of the BMU.
  • The verified evidence does not establish additional causes.

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

  • Arrange diagnosis by a qualified Mitsubishi EV service facility.
  • Have the stored DTC and the bulletin-specified battery sensor 1–6 checks evaluated with the specified diagnostic process.
  • Do not attempt high-voltage battery, CMU, or BMU repair yourself.

10. Step-by-step troubleshooting

  1. Use scan tool MB991958 as specified in the supplied bulletin evidence.
  2. Perform the bulletin-specified battery sensor 1–6 check.
  3. If the check result is not normal, the bulletin directs replacement of the Main Drive Lithium-ion Battery, then continuation to the next step.
  4. If the check result is normal, check whether the DTC is stored.
  5. If the DTC is stored, the bulletin directs replacement of the BMU.
  6. If the DTC is not stored, the bulletin states that the check is complete.

11. When to contact service

Service evaluation is appropriate because the documented procedure can require Main Drive Lithium-ion Battery or BMU replacement. The supplied evidence does not establish urgency, drivability, or charging restrictions.

12. What the service center may check

  • Confirm whether P1A90 is stored using scan tool MB991958.
  • Perform the specified battery sensor 1–6 check.
  • After normal check results, determine whether the DTC remains stored.

13. Possible repair or resolution

  • If the battery sensor 1–6 check result is not normal, replace the Main Drive Lithium-ion Battery, as directed by the bulletin.
  • If the battery sensor 1–6 check result is normal and the DTC is stored, replace the BMU, as directed by the bulletin.
  • If the battery sensor 1–6 check result is normal and the DTC is not stored, the bulletin states that the check is complete.

14. Affected vehicles

15. Related TSBs / service bulletins

  • TSB-19-54-004, published March 13, 2019. NHTSA manufacturer communication PDF 10158409: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158409-9999.pdf
  • TSB-19-54-003, published March 13, 2019. NHTSA manufacturer communication PDF 10158408: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158408-9999.pdf

16. Recall information

No recall relationship is established by verified evidence.

17. Official manufacturer information

Verified official evidence consists of NHTSA-hosted Mitsubishi manufacturer communications TSB-19-54-004 and TSB-19-54-003, both published March 13, 2019. The supplied evidence applies P1A90 to U.S. 2012 and 2014 Mitsubishi i-MiEV vehicles.

19. Frequently asked questions

What does P1A90 mean on a Mitsubishi i-MiEV?

The supplied Mitsubishi bulletin evidence identifies P1A90 as “CMU03 balancer abnormal.”

Which vehicles are established as applicable?

The supplied data establishes applicability for U.S.-market 2012 and 2014 Mitsubishi i-MiEV vehicles.

What does the bulletin direct if the battery sensor check is not normal?

It directs replacement of the Main Drive Lithium-ion Battery, followed by continuation to the next diagnostic step.

What does the bulletin direct if the sensor checks are normal but P1A90 remains stored?

It directs replacement of the BMU.

Is it safe to drive or charge with P1A90?

Not yet established by verified evidence.

20. Sources & verification

Verified
Mitsubishi P1A90: CMU03 balancer abnormal, P1A91: CMU04 balancer… | EV Diagnostics