Our 2003 has 292,500+ miles on it and started having a stumble at the beginning of accelerating from a stop. Replaced plugs and coils as it was throwing a relevant code. Also cleaned throttle body and MAF. Ran fine for a few weeks and now went into limp mode. Silly me took it in to the dealer asking them to do a deep scan and provide me a readout of DTCs with INFs, and Live Data. They basically gave me what I already knew P3125/302 and said, “ not worth fixing”. Over the phone the service writer had started reading the Live Data related to the DTC, but when I picked it up they did not provide a full printout, despite charging me $205 for the ‘diagnosis’… The P3125/302, indicates a W phase inverter voltage sensor issue as far as I can make out. Does anyone have any suggestions as to how I could further diagnose this?
AIUI about the only thing you can check…unless you're comfortable inspecting the internal electronics of the inverter…are the connections between the converter/inverter and the HV ECU. If they check out ok then it seems replacement is the only other option. There's a couple on eBay…but they're in the UK where I am…so you might be best checking breakers wherever you are. Best of luck, Jay.
For a 2001, the service manual suggests checking five wires between the inverter and the hybrid vehicle control ECU for continuity. Inverter HV ECU color I9-6 H11-26 black I10-1 H11-16 black I10-3 H11-7 white I10-4 H11-17 green I10-2 H11-25 red The last two (green and red) are associated with the W phase sensor, I think. At the inverter, I9 is a six-pin connector and I10 is an eight-pin connector. At the ECU, H11 is a 28-pin black connector. If all that checks out, it's "replace converter and inverter assembly". Again, this is for a 2001. I've heard that 2001, 2002, and 2003 are all the same, and then I've heard that 2001 and 2002 are the same, and 2003 is different. Your mileage may vary.
