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Mitsubishi P1D31

ROM/RAM Fail . TROUBLE JUDGMENT Check Condition  While the on board charger is allowed to be charged from the EV-ECU. Judgment Criterion  The ROM is abnormal (checksum is abnorma

DriveNot yet established by verified evidence.
ChargeNo while the P1D31 fail-safe is active: verified information states that charging is stopped.
ServiceService is appropriate because the official diagnostic procedure may require replacement of the on-board charger/DC-DC converter. The supplied record does not state a service-required status.
Confidence95%

Quick answer

P1D31 is a Mitsubishi i-MiEV on-board charger diagnostic trouble code for a ROM/RAM failure. Verified service information states that charging is stopped when this code is active.

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 P1D31 mean?

P1D31 is a Mitsubishi i-MiEV on-board charger diagnostic trouble code for a ROM/RAM failure. Verified service information states that charging is stopped when this code is active.

2. Technical explanation

For the 2012–2013 US Mitsubishi i-MiEV, P1D31 is evaluated while the EV-ECU permits charging. The code sets when the on-board charger detects either an abnormal ROM checksum or a RAM writing/reading error. The verified fail-safe action is that charging stops.

3. What system is affected?

On-board charger/DC-DC converter, specifically its ROM/RAM integrity monitoring.

4. How serious is this code?

The supplied record does not assign a severity level. However, the verified fail-safe function stops charging.

5. Symptoms you may notice

  • Charging stops when the P1D31 fail-safe is active.

6. Possible causes

  • Verified probable cause: failed on-board charger.
  • The code’s judgment criteria are an abnormal ROM checksum or a RAM writing/reading error in the on-board charger.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

No while the P1D31 fail-safe is active: verified information states that charging is stopped.

9. What you can safely do

  • Do not attempt high-voltage component repair.
  • Have the fault assessed using the manufacturer diagnostic procedure.
  • If charging is required, arrange professional service rather than attempting to bypass the charging stop.

10. Step-by-step troubleshooting

  1. Erase the DTC.
  2. Perform a regular charge.
  3. Check whether P1D31 resets.
  4. If P1D31 resets, the official procedure directs replacement of the on-board charger/DC-DC converter.
  5. If P1D31 does not reset, the official procedure identifies an intermittent malfunction and refers to Mitsubishi intermittent-malfunction diagnostic guidance.

11. When to contact service

Service is appropriate because the official diagnostic procedure may require replacement of the on-board charger/DC-DC converter. The supplied record does not state a service-required status.

12. What the service center may check

  • Confirm the DTC under the specified condition: while charging is permitted by the EV-ECU.
  • Clear the DTC and perform a regular charge.
  • Determine whether the DTC returns.
  • If it returns, follow the official replacement direction for the on-board charger/DC-DC converter.

13. Possible repair or resolution

  • If P1D31 is set again after DTC erasure and a regular charge, replace the on-board charger/DC-DC converter according to the official Mitsubishi procedure.
  • If it does not return, treat it as an intermittent malfunction per the referenced Mitsubishi diagnostic guidance.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Mitsubishi TSB-20-54-003, published through NHTSA as Manufacturer Communication PDF 10175779 on April 22, 2020. It includes the P1D31 diagnosis and directs replacement of the on-board charger/DC-DC converter if the code resets after clearing and a regular charge.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Verified source: NHTSA Manufacturer Communication PDF 10175779, Mitsubishi TSB-20-54-003: https://static.nhtsa.gov/odi/tsbs/2020/MC-10175779-9999.pdf

19. Frequently asked questions

What does P1D31 mean?

It means the on-board charger has detected a ROM/RAM failure condition: an abnormal ROM checksum or a RAM writing/reading error.

Will P1D31 stop charging?

Yes. The verified fail-safe and backup function states that charging is stopped.

What repair is specified if P1D31 returns?

After clearing the DTC and performing a regular charge, if P1D31 resets, the official procedure directs replacement of the on-board charger/DC-DC converter.

Does P1D31 mean the vehicle cannot be driven?

Not yet established by verified evidence.

20. Sources & verification

Verified
Mitsubishi P1D31: ROM/RAM Fail . TROUBLE JUDGMENT Check Condition … | EV Diagnostics