P0ac4 & u0100 Diagnostic Codes

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TheLondonBroiler

Well-known member
Joined
Oct 31, 2017
Messages
283
A week ago, I jumped in my car to go to work and the Service Vehicle Soon light was on. With no time to play, I jumped in my Corolla and went to work. Got home, read the codes (p0ac4 & u0100) and cleared them (figured they'd come back if there was really a problem). Thought I was in the clear until today, to my delight, when I started the car, the light was back on with the same codes. The vehicle drives fine (and continues to embarrass eager would-be right lane passers at stop lights). The problem apparently occurs during charging or at start up..... I guess.

I appreciate any constructive replies and I will follow up with what I find out. I think it's going to the dealer again and hopefully covered under manufacturer's warranty or by Carvana's warranty.....
 
TheLondonBroiler said:
A week ago, I jumped in my car to go to work and the Service Vehicle Soon light was on. With no time to play, I jumped in my Corolla and went to work. Got home, read the codes (p0ac4 & u0100) and cleared them (figured they'd come back if there was really a problem). Thought I was in the clear until today, to my delight, when I started the car, the light was back on with the same codes. The vehicle drives fine (and continues to embarrass eager would-be right lane passers at stop lights). The problem apparently occurs during charging or at start up..... I guess.

I appreciate any constructive replies and I will follow up with what I find out. I think it's going to the dealer again and hopefully covered under manufacturer's warranty or by Carvana's warranty.....

I recently had a similar experience with my 2015 Spark EV. The Service Vehicle Soon light came on and I could not get it to reset. So, I took it to the dealer - now the light went off - and the dealer read the codes and said I had a defective DCFC module. They also said I could use L1 and L2 charging but the DCFC option would not work. So, after I got the car back - the light was still off, I drove to a local DCFC and the car charged without any problem. What I did notice is I lost about 1.5 kWh in battery capacity. 6 weeks later the dealer removed the "defective" module and replaced it with the new replacement. Everything has been working fine since the module was replaced but I am still missing about 1 kWh in battery capacity. I will have to collect more data to be sure but the car continues to function perfectly. Your problem should be covered under the manufacturer's warranty. Mine was.
 
MrDRMorgan said:
So, after I got the car back - the light was still off

Driving home last night, I noticed the light had gone out... I'm sure it will be back.

MrDRMorgan said:
I drove to a local DCFC and the car charged without any problem.

I DCFC'ed this past Sunday, fortunately there were no problems either.

MrDRMorgan said:
What I did notice is I lost about 1.5 kWh in battery

Eek! No good. I'll keep an eye out.
 
TheLondonBroiler said:
MrDRMorgan said:
So, after I got the car back - the light was still off

Driving home last night, I noticed the light had gone out... I'm sure it will be back.

MrDRMorgan said:
I drove to a local DCFC and the car charged without any problem.

I DCFC'ed this past Sunday, fortunately there were no problems either.

MrDRMorgan said:
What I did notice is I lost about 1.5 kWh in battery

Eek! No good. I'll keep an eye out.
Yes, keep an eye on the Service Vehicle Soon light. I had one or two occasions where the light went on and, shortly thereafter, went out. I even tried disconnecting the negative battery terminal to reboot the computer. It worked once but didn't thereafter. My current calculated battery capacity is still running around 16 kWh which still gives me a full-charge range of about 90 miles. My 2014 is averaging 17.4 kWh and my 2016 is averaging 17.2 kWh. However, both the 2014 and 2016 have significantly fewer miles on the ODO than the 2015. The 2015, which has been basically trouble-free, is leased and will go back to the dealer in May with almost 30k miles on the ODO.
 
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