CheresX Posted 1 hour ago Share Posted 1 hour ago With 53k miles under the hood, I'm rocking a 2024 CX-90 PHEV. I am seeing the "Hybrid System Malfunction" message right now. Code P143B:00 was pulled by the dealer. My dealer replaced the 48 volt battery over the course of two visits. Swapped out the under-hood 12-volt battery at a later time. The error message disappeared for one day after the 12-volt battery was installed, but it later reappeared. The battery, which is about the size of a lawnmower, is located beneath the passenger floorboard. Remember that this went on for three months, and every time I started, I had to close the error message. In retrospect, I think the initial diagnosis was incorrect. Is anyone else going through the same thing? Quote Link to comment Share on other sites More sharing options...
CheresX Posted 1 hour ago Author Share Posted 1 hour ago Amazon.co.uk : Mazda CX-90 48 volt battery Quote Link to comment Share on other sites More sharing options...
CheresX Posted 1 hour ago Author Share Posted 1 hour ago Amazon.co.uk : Mazda CX-90 PHEV 12 volt car battery Quote Link to comment Share on other sites More sharing options...
Matt865 Posted 1 hour ago Share Posted 1 hour ago Found in the foot well area of the passenger compartment is the P143B, a 12V sub battery. I will be submitting my 2024 for this code next week. If you need help diagnosing or replacing the sub battery, this video should do the trick: Quote Link to comment Share on other sites More sharing options...
Matt865 Posted 1 hour ago Share Posted 1 hour ago  Quote Link to comment Share on other sites More sharing options...
Matt865 Posted 1 hour ago Share Posted 1 hour ago The battery that Mazda charges $250 for is available for less than $40 at Walmart or Amazon, so I would replace it myself if the warranty had expired. As an aside, the main battery of a PHEV is 355V (17.8KW), while the battery of a mild hybrid (one that is not a PHEV) is 48V. Assuming the hybrid battery was replaced under warranty, it's likely that you had multiple faults because Mazda would not have authorised the replacement without the associated testing and codes. Quote Link to comment Share on other sites More sharing options...
CheresX Posted 1 hour ago Author Share Posted 1 hour ago Oh no! Your explanation is much appreciated. The replacement was indeed the sub battery, as confirmed by the dealer when I contacted him. My apologies. We have now swapped out the 12 volt and the sub battery. There was no start-up error message on the day the 12-volt was replaced. Each start the following day brings an error message. On day three, you should see an error message about every other start. Today, after six starts, there was no error message. It seems like things are improving. Returning next Thursday for additional diagnostic testing. Quote Link to comment Share on other sites More sharing options...
Geek2232 Posted 1 hour ago Share Posted 1 hour ago That error message didn't appear until about 30 days after I purchased it used in April. Everything has been running smoothly ever since they changed the battery under the floorboard. Quote Link to comment Share on other sites More sharing options...
Blu_Ray_UK2007 Posted 1 hour ago Share Posted 1 hour ago Ignoring worries about hybrid batteries in the future is a smart move. These Hybrid gremlins aren't exclusive to Mazda, in my opinion. Giving up 10 mpg meant simplifying the system and eliminating the need to buy an expensive hybrid battery, both of which I did. Quote Link to comment Share on other sites More sharing options...
alpaco45 Posted 1 hour ago Share Posted 1 hour ago Exactly the same model with 36,000 miles on it just like this one. This money pit will soon be dumped. Quote Link to comment Share on other sites More sharing options...
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