Mitsubishi P1C04
Check output (B terminal) voltage reduction (Refer to DTC P1C04 DCDC output voltage reduction ). Then go to Step 2. NO : Go to Step 2. STEP 2. Connector check: E-03 on board charge
Quick answer
P1C04 is documented by Mitsubishi’s service procedure as a DC-DC converter output-voltage-reduction diagnostic for applicable 2012–2013 US Mitsubishi i-MiEV vehicles. The verified procedure begins by confirming the DTC, checking B-terminal output-voltage reduction, and inspecting the E-03 on-board charger/DC-DC converter connector and relay-box fuse No. 11 connection.
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 P1C04 mean?
P1C04 is documented by Mitsubishi’s service procedure as a DC-DC converter output-voltage-reduction diagnostic for applicable 2012–2013 US Mitsubishi i-MiEV vehicles. The verified procedure begins by confirming the DTC, checking B-terminal output-voltage reduction, and inspecting the E-03 on-board charger/DC-DC converter connector and relay-box fuse No. 11 connection.
2. Technical explanation
The supplied official Mitsubishi/NHTSA TSB evidence identifies P1C04 within a DC-DC converter diagnostic procedure. The procedure directs technicians to confirm whether P1C04 is set with scan tool MB991958, check for output-voltage reduction at the B terminal, and then perform a connector check at E-03 on the on-board charger/DC-DC converter and fuse No. 11 at the relay-box connector. If that connector check is not normal, the documented instruction is to repair the damaged connector and correct or replace the relay box.
3. What system is affected?
DC-DC converter output-voltage diagnostic circuit, including the B-terminal output-voltage check, E-03 on-board charger/DC-DC converter connector, and relay-box fuse No. 11 connection.
4. How serious is this code?
Not yet established by verified evidence.
5. Symptoms you may notice
- Verified evidence states that a P1C04 diagnostic procedure includes checking for DC-DC converter output-voltage reduction at the B terminal.
6. Possible causes
- Open circuit of the output S-terminal voltage circuit, connector damage, or poor connector contact.
- Open circuit of the output B-terminal voltage circuit.
- DC-DC converter failure.
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 provider.
- Do not attempt high-voltage or DC-DC converter repair procedures yourself.
- Provide the technician with DTC P1C04 and the vehicle year/model information.
10. Step-by-step troubleshooting
- A technician uses scan tool MB991958 to confirm whether P1C04 is set.
- If P1C04 is set, the procedure calls for checking B-terminal output-voltage reduction.
- Inspect connector E-03 at the on-board charger/DC-DC converter and the fuse No. 11 relay-box connector.
- If the connector check is normal, the documented procedure proceeds to a wiring-harness check between E-03 and the related circuit; the supplied evidence does not include the remainder of that step.
11. When to contact service
Service is recommended because the verified diagnostic procedure involves the DC-DC converter, its wiring/connectors, and relay-box connections. The supplied evidence does not establish whether immediate service is required.
12. What the service center may check
- Confirm P1C04 with scan tool MB991958.
- Check B-terminal output-voltage reduction as referenced by the Mitsubishi procedure.
- Check E-03 on-board charger/DC-DC converter connector condition and contact.
- Check fuse No. 11 at the relay-box connector.
- Check the wiring harness between E-03 and the related circuit; full details are not present in the supplied evidence.
13. Possible repair or resolution
- If the E-03/fuse No. 11 connector check is abnormal, repair the damaged connector.
- If applicable after diagnosis, correct or replace the relay box.
- The evidence lists DC-DC converter failure as a probable cause, but does not provide a verified replacement instruction in the supplied excerpt.
14. Affected vehicles
- Mitsubishi i-MiEV · 2012–2013 · US
15. Related TSBs / service bulletins
- Mitsubishi TSB-20-54-003, published April 22, 2020; NHTSA manufacturer communication MC-10175779-9999. The supplied excerpt contains the P1C04 diagnostic procedure and probable-cause list.
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Official source: NHTSA-hosted Mitsubishi manufacturer communication, TSB-20-54-003: https://static.nhtsa.gov/odi/tsbs/2020/MC-10175779-9999.pdf
19. Frequently asked questions
What does P1C04 apply to?
The supplied applicability evidence identifies 2012–2013 Mitsubishi i-MiEV vehicles in the United States.
What components are checked first for P1C04?
The documented procedure checks B-terminal output-voltage reduction, connector E-03 at the on-board charger/DC-DC converter, and fuse No. 11 at the relay-box connector.
Can a bad connector cause P1C04?
Yes. The official evidence lists connector damage or poor contact as a probable cause and instructs repair of a damaged connector when the connector check is abnormal.
Does P1C04 prove the DC-DC converter has failed?
No. DC-DC converter failure is listed as a probable cause, along with wiring and connector faults; the diagnostic checks are intended to distinguish among them.