ABS error C1241

Zabe · June 19, 2022

Hey guys,

Can someone please advise what the error C1241 under ABS is.

Error description is low or high power supply voltage.

Any idea what's causing this error?

Many thanks guys.

Zabe · June 19, 2022

I guess I'm the only unlucky one with this issue.

Herbie · June 19, 2022

I haven't got the workshop manual for a GS but this is for the RX450h and is probably the same.

Notice that the 12V Battery is the most likely cause in each case, so first thing I'd do would be to have that Battery load tested and see what the result is.

Zabe · June 20, 2022

3 hours ago, Herbie said:

I haven't got the workshop manual for a GS but this is for the RX450h and is probably the same.

Notice that the 12V battery is the most likely cause in each case, so first thing I'd do would be to have that battery load tested and see what the result is.

Thanks for the response, I will check my Battery to make sure its healthy. But its only been replaced with a genuine lexus one no more than 2 months ago!

Zabe · June 20, 2022

OK so I just checked the Battery and all is perfect with it. Anything else that can cause this?

Herbie · June 20, 2022

35 minutes ago, Zabe said:

OK so I just checked the battery and all is perfect with it

Given that it's only two months old you're most likely right, but did you just test it with a multimeter or did you do a proper load test with a proper Battery tester?

The multimeter can show, say, 12.8V but as soon as a load is applied that voltage could drop like a stone if the Battery has a bad cell.

35 minutes ago, Zabe said:

Anything else that can cause this?

Yes - any of the other things listed below 'Auxilliary battery' in the last column headed "Trouble Area". These are all things that could be at fault in order of likelyhood.

Zabe · June 20, 2022

Just now, Herbie said:

Given that it's only two months old you're most likely right, but did you just test it with a multimeter or did you do a proper load test with a proper battery tester?

The multimeter can show, say, 12.8V but as soon as a load is applied that voltage could drop like a stone if the battery has a bad cell.

Yes - any of the other things listed below 'Auxilliary battery' in the last column headed "Trouble Area". These are all things that could be at fault in order of likelyhood.

Ah I see, I did use a multimeter as that's all I have! Where can I get it tested properly?

Also any idea where the auxiliary Battery is located as I'll just get a new one from lexus as its never been changed!

Herbie · June 20, 2022

7 minutes ago, Zabe said:

Ah I see, I did use a multimeter as that's all I have! Where can I get it tested properly?

Also any idea where the auxiliary battery is located as I'll just get a new one from lexus as its never been changed!

Almost any car accessory shop that sells batteries will be able to test it for you, or somewhere like KwikFit, National or even Halfords.

I've never had a GS so I don't know where the Battery is, but I'm thinking it can only be in the engine bay or the boot. In my RX it's under the boot floor.

EDIT - I'm trying to do half a dozen things at once today so I didn't notice at first but something seems a bit fishy here.

First you say that the Battery is only two months old and that you've tested it to be ok, but then you ask "where the auxiliary Battery is located as I'll just get a new one from lexus as its never been changed! "

What's going on?

Zabe · June 20, 2022

4 minutes ago, Herbie said:

Almost any car accessory shop that sells batteries will be able to test it for you, or somewhere like KwikFit, National or even Halfords.

I've never had a GS so I don't know where the battery is, but I'm thinking it can only be in the engine bay or the boot. In my RX it's under the boot floor.

OK thanks for that. I'll go to kwikfit or Halfords now!

Also just to clarify, are referring to another Battery apart from the 12V one in the boot of the car?

Zabe · June 20, 2022

2 hours ago, Herbie said:

Almost any car accessory shop that sells batteries will be able to test it for you, or somewhere like KwikFit, National or even Halfords.

I've never had a GS so I don't know where the battery is, but I'm thinking it can only be in the engine bay or the boot. In my RX it's under the boot floor.

EDIT - I'm trying to do half a dozen things at once today so I didn't notice at first but something seems a bit fishy here.

First you say that the battery is only two months old and that you've tested it to be ok, but then you ask "where the auxiliary battery is located as I'll just get a new one from lexus as its never been changed! "

What's going on?

The Battery in the boot has been changed with a new one from lexus 2 months ago.

This is the 12V Battery. When you said Auxiliary Battery I thought you was referring to another Battery.

Herbie · June 20, 2022

18 minutes ago, Zabe said:

The battery in the boot has been changed with a new one from lexus 2 months ago.

This is the 12V battery. When you said Auxiliary battery I thought you was referring to another battery.

Aha, right, I see the confusion.

The 12V Battery is often referred to as the auxilliary or starter, because the main Battery in a hybrid is the high voltage traction Battery (depends on model but this is usually somewhere around 300V) and you don't want to be messing around with that unless you have the necessary PPE, tools and you know exactly what you're doing.

Zabe · June 20, 2022

1 minute ago, Herbie said:

Aha, right, I see the confusion.

The 12V battery is often referred to as the auxilliary or starter, because the main battery in a hybrid is the high voltage traction battery (depends on model but this is usually somewhere around 300V) and you don't want to be messing around with that unless you have the necessary PPE, tools and you know exactly what you're doing.

Yes I luckily do know that and apologies for the misunderstanding.

So Halfords tested the Battery and said its fine so now I'm back to square one again.

Herbie · June 20, 2022

Just sent you a PM that may help Zabe.

Zabe · June 20, 2022

1 hour ago, Herbie said:

Just sent you a PM that may help Zabe.

Thanks, appreciate that!

Blizzard2k · November 20, 2023

On 6/20/2022 at 11:43 AM, Herbie said:

Just sent you a PM that may help Zabe.

Any advice you could send my way? My 2009 IS250 also has the C1241 and a C1424 both under ABS. I will load test the Battery tonight and see if its a bad Battery. My DRLs also flicker. But when i turn on the low beams they stop. Wondering if that's related.