Mitsubishi P1B21
Return to Step 1. NO : The diagnosis is complete. DTC P1B0D Quick charging current error (overcurrent) CAUTION If there is any problem in the CAN bus lines, an incorrect DTC may be
Quick answer
P1B21 is documented in Mitsubishi service procedures for certain U.S. i‑MiEV model years. The supplied evidence does not establish a plain-language fault definition for P1B21 itself. Mitsubishi’s procedure directs EV-ECU diagnosis and, if P1B21 remains after the specified verification, EV-ECU 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 P1B21 mean?
P1B21 is documented in Mitsubishi service procedures for certain U.S. i‑MiEV model years. The supplied evidence does not establish a plain-language fault definition for P1B21 itself. Mitsubishi’s procedure directs EV-ECU diagnosis and, if P1B21 remains after the specified verification, EV-ECU replacement.
2. Technical explanation
Official Mitsubishi service material groups P1B21 with P1B0C in a diagnostic confirmation procedure. It instructs technicians to erase stored DTCs, connect the regular charging cable/connector, and check whether P1B0C or P1B21 returns. If either code remains, the procedure directs replacement of the EV-ECU and then rechecking. The supplied excerpts immediately continue into a separate P1B0D quick-charging overcurrent diagnostic; that P1B0D description must not be treated as the meaning of P1B21.
3. What system is affected?
EV-ECU is explicitly identified in the verified diagnostic procedure. A broader system assignment 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
- The verified procedure identifies the EV-ECU as the component to replace if P1B21 remains after the prescribed erase, regular-charge connection, and recheck procedure.
- Additional causes of P1B21 are 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?
The verified procedure uses connection of the regular charging cable/connector as part of a technician diagnostic confirmation. Whether the vehicle is generally safe or able to charge with P1B21 is not yet established by verified evidence.
9. What you can safely do
- Arrange diagnosis by a qualified Mitsubishi EV service technician.
- Do not attempt high-voltage or EV-ECU repair procedures yourself.
- Provide the stored code and vehicle model year to the service facility.
10. Step-by-step troubleshooting
- A technician procedure in the supplied Mitsubishi material is to erase stored DTCs, connect the regular charging cable/connector, and check whether P1B0C or P1B21 is stored or set again.
- If P1B0C or P1B21 is still present after that verification, the procedure directs replacement of the EV-ECU, followed by another check for the code.
- The supplied evidence does not establish additional owner-level troubleshooting steps.
11. When to contact service
Service is appropriate because the verified Mitsubishi procedure can direct EV-ECU replacement when P1B21 persists after its specified confirmation check.
12. What the service center may check
- Read and record EV-ECU DTCs.
- Perform the Mitsubishi-specified erase-and-recheck procedure using the regular charging cable/connector.
- If P1B21 remains, follow the documented EV-ECU replacement direction and recheck for the DTC.
13. Possible repair or resolution
- Verified Mitsubishi procedure: replace the EV-ECU if P1B21 remains after the specified confirmation process.
- After replacement, the procedure calls for checking again whether the DTC is set or stored.
14. Affected vehicles
- Mitsubishi i-MiEV · 2012 · US
- Mitsubishi i-MiEV · 2014 · US
- Mitsubishi i-MiEV · 2016 · US
15. Related TSBs / service bulletins
- Mitsubishi TSB-19-54-003, published March 13, 2019; NHTSA Manufacturer Communication 10158408.
- Mitsubishi TSB-19-54-004, published March 13, 2019; NHTSA Manufacturer Communication 10158409.
- Mitsubishi TSB-19-54-005, published March 13, 2019; NHTSA Manufacturer Communication 10158410.
16. Recall information
No recall relationship is established by verified evidence.
17. Official manufacturer information
Verified official source: NHTSA-hosted Mitsubishi manufacturer communications dated March 13, 2019. TSB-19-54-003: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158408-9999.pdf ; TSB-19-54-004: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158409-9999.pdf ; TSB-19-54-005: https://static.nhtsa.gov/odi/tsbs/2019/MC-10158410-9999.pdf
19. Frequently asked questions
What does P1B21 mean?
The supplied verified excerpts do not provide a standalone plain-language definition for P1B21. They document it as an EV-ECU DTC handled alongside P1B0C in a Mitsubishi diagnostic procedure.
Which vehicles are covered by the supplied evidence?
Mitsubishi i‑MiEV vehicles in the U.S. for model years 2012, 2014, and 2016.
Does P1B21 mean quick-charging overcurrent?
Not established. The supplied excerpts label P1B0D—not P1B21—as quick-charging current error/quick-charging overcurrent.
What repair does the procedure specify if P1B21 returns?
The documented procedure directs replacement of the EV-ECU if P1B21 remains after the specified erase, regular-charge connection, and recheck process.