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Mitsubishi P1B74

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. The official diagnostic procedure uses quick charging or external power-supply equipment during a controlled DTC recheck, but this does not establish that ordinary charging is safe or unsafe when P1B74 is present.
ServiceContact a Mitsubishi EV-qualified service facility for diagnosis. The documented process requires a scan tool, CAN-bus diagnosis, and charging or external-power equipment.
Confidence95%

Quick answer

P1B74 is a Mitsubishi EV diagnostic trouble code documented for U.S.-market 2014 and 2016 i-MiEV vehicles. Verified Mitsubishi diagnostic material directs technicians to check CAN-bus lines, recheck the code during complete charging or discharging using quick-charging or external power-supply equipment, and perform a current-sensor check. One official procedure directs BMU replacement when P1B74 remains stored at the applicable step.

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 P1B74 mean?

P1B74 is a Mitsubishi EV diagnostic trouble code documented for U.S.-market 2014 and 2016 i-MiEV vehicles. Verified Mitsubishi diagnostic material directs technicians to check CAN-bus lines, recheck the code during complete charging or discharging using quick-charging or external power-supply equipment, and perform a current-sensor check. One official procedure directs BMU replacement when P1B74 remains stored at the applicable step.

2. Technical explanation

The supplied verified evidence identifies P1B74 as an EV-ECU DTC. Mitsubishi’s documented diagnostic flow begins with CAN-bus diagnosis because a CAN-bus problem can store an incorrect DTC. If the CAN check is abnormal, the procedure calls for CAN-bus-line repair and then a DTC recheck. The recheck consists of erasing the DTC, connecting the quick-charging connector or external power-supply equipment to completely charge or discharge the battery, and checking whether P1B74 resets. If it resets, the procedure continues to a current-sensor check. A separate official procedure states that, when P1B74 is stored at its specified decision point, the BMU is replaced, followed by another DTC recheck in the EV-ECU.

3. What system is affected?

EV-ECU, CAN-bus communication lines, current-sensor diagnostic path, and BMU are referenced in the verified Mitsubishi procedures. The exact failed component for an individual vehicle is not yet established by verified 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

  • A problem in the CAN-bus lines may cause an incorrect DTC to be stored, according to the Mitsubishi procedure.
  • A current-sensor issue is included in the official diagnostic path, but the supplied evidence does not establish it as the cause for every P1B74 case.
  • A BMU-related condition is addressed by the official procedure when P1B74 remains stored at the specified diagnostic step.

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. The official diagnostic procedure uses quick charging or external power-supply equipment during a controlled DTC recheck, but this does not establish that ordinary charging is safe or unsafe when P1B74 is present.

9. What you can safely do

  • Have the vehicle evaluated using the applicable Mitsubishi diagnostic procedure.
  • Record whether the code returns after it is cleared; this recheck should be performed by qualified personnel using the specified equipment.
  • Do not attempt high-voltage battery, charging-system, CAN-bus, current-sensor, or BMU repair yourself.

10. Step-by-step troubleshooting

  1. Using scan tool MB991958, diagnose the CAN-bus lines.
  2. If the CAN-bus check is not normal, repair the CAN-bus line according to the referenced Mitsubishi troubleshooting procedure, then recheck P1B74.
  3. Erase the DTC.
  4. Connect the quick-charging connector or external power-supply equipment to completely charge or discharge the battery.
  5. Check whether P1B74 is set again in the EV-ECU.
  6. If P1B74 remains set, continue with the current-sensor check specified by Mitsubishi.
  7. One official procedure directs BMU replacement if P1B74 is stored at its specified decision point, then requires another EV-ECU DTC recheck.

11. When to contact service

Contact a Mitsubishi EV-qualified service facility for diagnosis. The documented process requires a scan tool, CAN-bus diagnosis, and charging or external-power equipment.

12. What the service center may check

  • Check CAN-bus lines with scan tool MB991958.
  • Recheck P1B74 after clearing the code and completely charging or discharging the battery with the specified equipment.
  • Perform the current-sensor check when directed by the diagnostic flow.
  • Recheck stored DTCs in the EV-ECU after the applicable repair step.

13. Possible repair or resolution

  • If CAN-bus diagnosis is abnormal, the documented procedure calls for repair of the CAN-bus line followed by a DTC recheck.
  • If P1B74 remains stored at the specified step in the official procedure, replace the BMU and continue with the prescribed EV-ECU DTC recheck.
  • The final repair for a specific vehicle is not yet established by verified evidence and depends on diagnostic results.

14. Affected vehicles

15. Related TSBs / service bulletins

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

16. Recall information

No recall relationship is established by verified evidence.

17. Official manufacturer information

Verified applicability: Mitsubishi i-MiEV, U.S. market, model years 2014 and 2016. Official source evidence is from Mitsubishi manufacturer communications hosted by NHTSA. No recall information is supplied in the verified evidence.

19. Frequently asked questions

What does P1B74 mean on a Mitsubishi i-MiEV?

The supplied record labels P1B74 as an EV-ECU DTC and includes a prescribed recheck procedure: erase the DTC, connect quick-charging or external power-supply equipment to completely charge or discharge the battery, then check whether the DTC sets again. A fuller component-level meaning is not yet established by verified evidence.

Can a CAN-bus fault cause P1B74?

Mitsubishi states that a problem in the CAN-bus lines can cause an incorrect DTC to be stored and instructs technicians to diagnose CAN-bus lines before this diagnostic path.

Does P1B74 require BMU replacement?

Not in every case. The official procedure directs BMU replacement only when P1B74 is stored at a specified point in its diagnostic flow. CAN-bus and current-sensor checks are also part of the documented process.

Which vehicles are covered by the supplied evidence?

U.S.-market 2014 and 2016 Mitsubishi i-MiEV vehicles.

20. Sources & verification

Verified
Mitsubishi P1B74: ECU. (1) Erase the DTC. (2) Connect the quick… | EV Diagnostics