P3004: How to Diagnose & Fix — High Voltage Power Resource Circuit Malfunction
2 vehicles · 1 makes · $2,500-$5,000 repair
How to diagnose and fix P3004: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Toyota Crown · 2023–2023
Some 2023 Crown hybrids illuminate the hybrid system warning lamp / check engine light when operated in below-freezing temperatures (below 32F / 0C). The condition is a false high-voltage power-resource circuit short detected during Ready-ON or pre-charge, logged as DTCs P1C8449 and/or P300449. The CarComplaints 2023 Crown TSB page confirms the bulletin applies to the Crown.
Common Symptoms
- Hybrid system warning lamp on in cold weather
- Check engine / malfunction indicator lamp after cold starts
- Warning lights appear below 32F and may clear when warm
- DTCs P1C8449 or P300449 stored
How to Fix
Toyota TSB T-SB-0085-23 (CarComplaints TSB008523, published Nov 1, 2023). After a Health Check confirms DTC P1C8449 and/or P300449, the dealer performs the bulletin's repair procedure to resolve the false cold-weather high-voltage circuit-short detection.
Sources for this issue (2)
Toyota Prius · 2010–2015
Transistors inside the Intelligent Power Module of the inverter/converter assembly can overheat and fail under sustained high load (long grades, hard acceleration, hot weather). When the module faults, the hybrid system shuts down and the car can stall at speed, sometimes without warning. Toyota first issued a software recall to reduce IPM thermal stress (NHTSA 14V-053, ~701,000 US Gen 3 cars), later expanded remedies (18V-684), and created Customer Support Program ZE3 extending inverter coverage on 2010-2014 Prius to 15 years/unlimited miles. Owners report stalls persisting after the software remedy, which drove follow-on litigation. This is failure of the inverter itself - distinct from the inverter coolant pump.
Common Symptoms
- Vehicle stalls or loses power at highway speed
- Red triangle hybrid warning and check engine light
- Limp-home / reduced power mode
- Car will not restart until cooled or after a reset
- Burning smell from under the hood in severe cases
How to Fix
Verify the recall/CSP status by VIN at the NHTSA or Toyota owners site and have the software remedy applied if outstanding. If the IPM has actually failed, the fix is replacement of the inverter/converter assembly (Toyota does not sell the IPM separately), followed by a full inverter coolant fill and air bleed - and the inverter coolant pump should be checked at the same time, because a weak pump is a common contributor to IPM overheating. Push for ZE3 coverage on 2010-2014 cars before paying out of pocket.
Sources for this issue (3)
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P3004 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P3004 mean?
P3004 stands for "High Voltage Power Resource Circuit Malfunction." Toyota's hybrid repair manuals title this code 'High Voltage Power Resource' malfunction: the hybrid/power management control ECU has detected a fault in the high-voltage supply path between the traction battery and the inverter with converter assembly. Toyota bulletin T-SB-0085-23 defines sub-code P300449 specifically as 'High Voltage Power Resource Circuit Short during Pre-Charge' - a short detected while the inverter's capacitors are being pre-charged before Ready. In practice the code most often resolves to a failed Intelligent Power Module (IPM) inside the inverter assembly, and Toyota's IPM programs (CSP 23TE03) list P3004 as a qualifying code; in freezing weather it may instead be the software condition addressed by T-SB-0085-23.
What are the most common causes of P3004?
The most common causes of P3004 are: Intelligent Power Module (IPM) failure inside the inverter assembly, typically from thermal stress, Inverter with converter assembly internal fault, Short or insulation breakdown in the high-voltage power cable between the HV battery and inverter, Hybrid control software condition in below-freezing temperatures (Toyota T-SB-0085-23; fixed by reflash), MG ECU fault within the inverter. The specific cause varies by vehicle.
How much does it cost to fix P3004?
Repair costs for P3004 range from $2,500 to $5,000, depending on the vehicle and root cause.
Which vehicles are affected by P3004?
Au7o has documented P3004 across 2 vehicle models from 1 manufacturers: Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.