Behind the Diagnosing Scenes: Frozen Hybrid Battery Edition

It’s 2017 and with a new year comes new resolutions. This year we want to focus on auto repair education. We know that if you’re not an auto technician, it can be hard to understand what’s wrong and why it’s a problem. In response to this, we are going to be publishing educational videos that help you understand our diagnosis process. Hopefully, in the process, we can answer some the “how’s” and “why’s” you’ve always wondered about. We’re kicking off our project with a video about a hybrid battery repair that came into the shop recently, specifically a Battery Isolation Fault Code P0AA6. While hybrids are a great economically and environmentally, they can be difficult to diagnose if you’re not sure what you’re doing. This diagnosis was the same.

Watch our video below to see exactly what happened:

The Diagnosis Process:

Hybrids are built with safety features that are meant to protect drivers and their passengers from harm. Those safety features are exactly why this hybrid came into the shop. Because the water exposure caused the battery to leak voltage, the vehicle refused to start because of Isolation Fault Code P0AA6. Hybrid batteries are extremely powerful and can do a lot of damage if the battery’s voltage were to leak, including possible electrocution to the car and its passengers. Yikes! This is why there is a built in safety feature to prevent dangerous situations like this.

After removing the battery and doing some detective work, we found that there were several problems contributing to the activation of the Battery Isolation Fault Code P0AA6. There had been a large amount of water around the battery, and in our weather, some of that water froze. Also the drain below the battery had been clogged with loose debris. Because the drain had been clogged, the water swelled around the battery and ultimately froze. While you would think the problem is the clogged drain, there is not actually supposed to be water running through the car at all.

After a thorough investigation, we found a water spot in the upholstery at the top of the trunk, which resulted in us finding a body pinch welded sealant that was cracking. This crack was letting in water that pooled and froze around the battery. We quickly resealed the body pinch, replaced the drain, and dried the battery, after testing it to be sure it wasn’t permanently damaged.

Luckily the safety feature kicked in and threw the code P0AA6, refusing to let this hybrid start. This is why it’s important to listen to your vehicle and take it to a professional if needed. Our detectives, I mean technicians, know what clues and signs to look for while diagnosing your vehicle in order to repair the problem and prevent it in the future. We also believe in the importance of educating our customers. We believe that if you better understand what the “what’s” and “why’s”, you’ll be happier in the long run.

Be sure to keep an eye out for our new videos on our Facebook page, our youtube page, and in any upcoming blogs!

Written by Dan Garlock

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