Toyota Prius Inverter Water Pump Replacement

August 14, 2013 — Leave a comment

Sunday evening:

As I was putting away the tools from working around the lawn, I noticed that Sarah had returned from running errands.  She casually mentioned that on the drive home, her Prius had displayed some warnings and she’d like for me to check it out.  The way she nonchalantly described the issue, I assumed that it was another “take me to the dealer” idiot light and began to investigate.

Upon inspection, this appeared to be more serious than just a benign warning light.  Just about every warning/error light on the dash was illuminated.  Worse yet, I inspected the engine bay before diving into the errors and thought the electric motor was unusually HOT.  We had just driven the car back from Florida the day before without any problems and even after 12 hours on the road, the engine wasn’t as hot as it was now.

I asked Sarah to explain what the car’s behavior when the errors appeared.  She said she didn’t notice much of a performance difference in the car but the electronics weren’t working and the air conditioning began blowing hot air.  We’ve experienced similar issues in the past that was attributed to a bad 12 volt battery.  But the sizzling inverter under the hood left me prepared for the worst.

The first thing I inspected was the diagnostic codes the Prius computer to see what diagnostic codes it was providing:

Prius LAN Monitor

Using some Google-fu, I determined that these diagnostic codes weren’t very helpful at all.  I needed to know what check engine codes the car was generating and I wasn’t comfortable driving it 3-4 miles to the nearest auto parts store.  I couldn’t think of anyone with an OBD2 reader, so I bit the bullet and purchased an Actron Pocketscan Code Reader CP9125.  Turns out it’s currently on sale for $49 at Advance Auto Parts.  The Advance sales associate tried to up-sell me on an upgraded model that would immediately describe what the error code meant — but I didn’t think I needed that; That’s what the Internet is for. 🙂

The code reader gave me what I soon discovered is the infamous P0A93 code. Apparently there was a recall of several years worth of Priuses due to faulty inverter water pumps.  Our Prius VIN didn’t say we were eligible for the recall and given that we’re pushing 123,000 miles on the car, a water pump failure isn’t surprising.

In summary, I found a few things that I wanted to share with any other Prius owners looking for a solution to this same problem:

Luscious Garage has the best summary I’ve found regarding this problem.  You can read their write-up here or watch a video they posted about it on YouTube.

I also found the part number and price they provided, G9020-47031 & $138 to be accurate for the replacement part directly from my local Toyota dealer.

This PDF on PriusChat was also useful in providing some troubleshooting steps before replacement.

I experienced some difficulty moving the inverter enough to remove the water pump and the clearance was tight — but it wasn’t as big a pain in the butt as replacing HID bulbs.

In the end, it turns out the pump was in fact dead. The coolant was a little low (but not below the low-level line) and it was not circulating in the system with the IGN-ON.  If Luscious Garage bills 75 minutes of labor, I’m pleased to complete the entire project in about 140 minutes.

So far, I haven’t encountered any repair job on the Prius that’s required service at the Stealership — and I hope it stays that way. 🙂

Aaron Melton


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