Replacing the Hybrid Inverter in a 2002 Prius

Lb50921 · Jul 23, 2011

I bought a 2002 Prius from a used car lot about ten months ago and have really enjoyed driving it (43 miles/gal). However for the past four months the check engine light would come on occasionally during the warmest parts of the day and would turn off at night or after cooling off. Yesterday the light came on but this time it actually started powering down--on the road! I had it towed to the repair shop at a local dealership. They called me this morning for the diagnosis: my Hybrid Inverter is completely dead and as a result the water pump also has to be replaced. They quoted me at $4,950 for the repairs. Mind you I'm still paying for this car (it was $4,000 and I'm halfway through my payments) and it has 200,000 miles. The mechanic at the dealership said they used to use parts from totaled Prius' but after realizing that the inverter would just carry over issues from the previous car into the transplant car they stopped and now only replace with new inverters. I'm wondering if this is true and if I could keep my prius and have some other shop do an inverter transplant for much less than $4,000. Any suggestions? Thanks!

Phoenix · Aug 13, 2011

Years ago, the hybrid coolant pump went out on our 2002 Prius. You may be able to get by with just replacing the pump (if the hybrid module didn't actually fail), which will probably only be $300-400. I think the pump is around $150 (and it looks like it is worth about $35), and the rest is labor. Personally, I'd check to see if the car will start normally and then just change the pump, because the system is supposed to have some logic that protects the boards when overheated. Then, I'd revisit replacing the hybrid module if you still get failure lights or the car won't run.

As far as replacing with a new module, the dealer probably doesn't want to mess around with used parts. They have probably gotten burned before. Please note that in the early days, the modules were being updated a couple of times a year. Your Prius (and ours) are quite dated compared to the new models, and the hybrid module has probably been changed significantly. However, any replacement module is probably one that has been on the shelf since 2002 or 2003 when the design changed. So, considering the price for a "new" one from the dealer, I'd consider a used one from alternative sources.

If you do get a used one, please note that our 2002 Prius' module has PROMS soldered directly onto the printed circuit board. When our pump broke, Toyota replaced the module with a new PCB that had EPROMS in sockets, so that the memory could be reprogrammed without replacing the board. If you get a used module, it would be preferable to get a later-designed board if possible; although, this may not be something you have any control over.

Replacing the Hybrid Inverter in a 2002 Prius

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