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Mitsubishi P1B73

ECU. (1) Erase the DTC. (2) Connect the quick charging connector or an external power supply equipme nt to charge or discharge the battery completely. (3) Check if the DTC is set

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceProfessional EV service is appropriate because the verified procedure involves high-voltage charging or discharging equipment and system-level diagnosis. Whether service is mandatory is not established by the supplied evidence.
Confidence95%

Quick answer

P1B73 is documented by Mitsubishi service information for certain U.S. 2014 and 2016 i-MiEV vehicles. Verified diagnosis includes clearing the DTC, connecting quick-charging or external power-supply equipment to fully charge or discharge the battery, and checking whether P1B73 resets. Do not perform this procedure without appropriate EV service capability.

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 P1B73 mean?

P1B73 is documented by Mitsubishi service information for certain U.S. 2014 and 2016 i-MiEV vehicles. Verified diagnosis includes clearing the DTC, connecting quick-charging or external power-supply equipment to fully charge or discharge the battery, and checking whether P1B73 resets. Do not perform this procedure without appropriate EV service capability.

2. Technical explanation

The supplied official Mitsubishi TSB evidence describes a recheck procedure for P1B73 in the EV-ECU. After CAN bus-line diagnosis or reset, the procedure is to erase the DTC, connect the quick-charging connector or external power-supply equipment to charge or discharge the battery completely, then check whether the DTC is set again. If it does not reset, the diagnosis is complete. The evidence also identifies a current-sensor check as a subsequent diagnostic step when P1B73 remains set. Another supplied TSB excerpt states that, at a specified point in its diagnostic sequence, if P1B73 is stored, the BMU is to be replaced, followed by another DTC recheck. The full decision sequence and conditions for that replacement are not fully established by the supplied excerpts.

3. What system is affected?

EV-ECU; the supplied evidence also references CAN bus lines, a current-sensor check, quick-charging/external power-supply equipment, and the BMU.

4. How serious is this code?

Unknown. Severity is not established by the verified evidence.

5. Symptoms you may notice

  • Not yet established by verified evidence.

6. Possible causes

  • A CAN bus-line problem can result in an incorrect DTC being stored, according to the supplied Mitsubishi TSB evidence.
  • The supplied evidence requires a current-sensor check if P1B73 remains set after the DTC recheck; a specific current-sensor fault cause is not established by the excerpt.
  • At a specified point in the Mitsubishi diagnostic procedure, a stored P1B73 leads to BMU replacement. The underlying BMU failure mode is not established by the supplied 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

  • Arrange diagnosis by a Mitsubishi-capable EV service facility.
  • Provide the technician with DTC P1B73 and the applicable Mitsubishi TSB references.
  • Do not attempt high-voltage battery charging, discharging, CAN-bus repair, current-sensor testing, or BMU replacement yourself.

10. Step-by-step troubleshooting

  1. The official procedure first calls for CAN bus-line diagnosis before this diagnosis because a CAN bus-line problem may store an incorrect DTC.
  2. After CAN bus-line reset/repair, erase P1B73 and recheck it after using the quick-charging connector or external power-supply equipment to fully charge or discharge the battery.
  3. If P1B73 does not reset during the recheck, the supplied procedure states that diagnosis is complete.
  4. If P1B73 remains set, the supplied procedure proceeds to a current-sensor check and later diagnostic steps.
  5. A separate supplied TSB excerpt instructs BMU replacement when P1B73 is stored at the indicated stage, then requires another DTC recheck.

11. When to contact service

Professional EV service is appropriate because the verified procedure involves high-voltage charging or discharging equipment and system-level diagnosis. Whether service is mandatory is not established by the supplied evidence.

12. What the service center may check

  • Diagnose CAN bus lines before P1B73 diagnosis, as specified in the Mitsubishi TSB.
  • Erase and recheck P1B73 after the prescribed full charge or discharge using quick-charging or external power-supply equipment.
  • Perform the current-sensor check if P1B73 remains set, per the supplied procedure.
  • Follow the applicable Mitsubishi diagnostic sequence for BMU replacement and post-replacement DTC recheck.

13. Possible repair or resolution

  • Repair the CAN bus line if its check result is not normal, as stated in the supplied Mitsubishi TSB.
  • Replace the BMU when directed by the applicable step in the Mitsubishi diagnostic procedure, then recheck for P1B73.
  • No further repair resolution is established by the supplied evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Mitsubishi TSB-19-54-004, published March 13, 2019; NHTSA manufacturer communication MC-10158409: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158409-9999.pdf
  • Mitsubishi TSB-19-54-005, published March 13, 2019; NHTSA manufacturer communication MC-10158410: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158410-9999.pdf

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Official NHTSA-hosted Mitsubishi TSB evidence applies P1B73 diagnostic information to U.S. 2014 and 2016 Mitsubishi i-MiEV vehicles. Applicability beyond those supplied records is not established by verified evidence.

19. Frequently asked questions

What does P1B73 mean on an i-MiEV?

The supplied record labels P1B73 with a Mitsubishi EV-ECU diagnostic recheck procedure rather than a plain-language fault description. It requires clearing the code, using quick-charging or external power-supply equipment to fully charge or discharge the battery, and checking whether the code resets.

Can a CAN bus problem cause P1B73?

The supplied Mitsubishi TSB states that a CAN bus-line problem can cause an incorrect DTC to be stored and directs CAN bus-line diagnosis before this diagnostic process.

Does P1B73 require BMU replacement?

One supplied Mitsubishi TSB excerpt directs BMU replacement if P1B73 is stored at a specified stage of its diagnostic sequence. The excerpts do not establish that every occurrence of P1B73 requires BMU replacement.

Can I keep driving or charging with P1B73?

Not yet established by verified evidence.

20. Sources & verification

Verified
Mitsubishi P1B73: ECU. (1) Erase the DTC. (2) Connect the quick… | EV Diagnostics