Ronock

Sorry guys, just realized I never updated this post despite fixing it so for anyone who finds themselves in a similar situation. I load tested each cell again as was recommended and actually found that all the cells dropped in their readings towards the 22nd cell in the row before that cell in particular fell to bellow 6 so it seemed like a bad cell that was effecting all the others. After buying a new cell online and replacing it all the issues went away, definitely beats the Lexus dealership £4000 offer to fix it. Another massive thanks to the people that replied in this chat

Thanks for the help, guess I've got a few more options to work through now and hopefully by the end it I'll have a better idea of what's happened

The code was up when they scanned it, but what you are saying is for an accurate diagnostic i need to drive round with all the codes active until it can give a more accurate error? Also yeah all the Voltage readings were just done with a multimeter but my assumption was a faulty cell would read different than the others regardless but i guess that's wrong I'll be taking the whole hybrid unit out again soon, is there any way i can test the sensors or the circuitry while its out to eliminate them as possibilities?

So i've owned my 2007 GS450h for about a year now, a few months ago I started getting a sudden barrage of lights and error messages and the hybrid system would shut off; the car was still drivable but would only utilize the engine. 3 error messages would always appear, Check ECB, Check VSC and Check Hybrid battery. Originally i stopped driving it all together until i got the code read and wiped, the code was P0A80 to replace the hybrid battery. Once the code was wiped however the car drove totally normally, the battery recharged as normal and was driving as good as new. However after driving it for any prolonged amount of time the issue would reappear along with all the lights and error messages, but i realized i could just disconnect the battery and reconnect it when it happened and the car would lose all the saved errors and drive perfectly fine again; It was only while the error was on the dash that the hybrid system was turned off. So i wasn't in any urgent rush to fix it because it was only a mild inconvenience, over the next couple of months i tried a few fixes which included checking some fuses and getting a new 12V battery. Nothing worked. So last week i took the entire battery out of the car and reconditioned some parts of it, the connections between all the terminals were corroded so i cleaned all of them up, i checked all wires and connections which all seemed fine and all of the voltage's read within 0.05 of each other (All were at around 8). After reinstalling the battery the car ran much better and i thought my issue would be fixed, however it took about 50 miles of driving and suddenly all the errors returned and i was back to disconnecting the battery every 10/20 miles to reset the codes. Lexus said they can't diagnose the problem and simply said it would cost 4/5k to replace the battery which is obviously lunacy because the entire system works fine, i just need to know what's triggering the codes to appear. Has anyone got any idea? it happens seemingly at random with only thing that increases consistency is amount of time driven but sometimes it would just happen again and again after only a few miles. Desperately looking for solutions now because any other professionals give me the same answer and i can't really afford to replace the whole system