MG 4 TJA failure.

[redmg4]

The TJA failed when the car was serviced at the end of November. Before that it only worked when hje car was set yo miles. I live in Spain so usually have it set too km.Now it does not work at all. My dealer looked at the car but said they could not do anything. Are there any fixes l can try at home rather than return to the dealer?
Love driving this car but anything to do with the computer seems a bit random!

 

[DonBattino452]

Greetings from GER ! It could be a software issue but without a VCI interface you can't get further information. It seems that your MG dealer isn't willing to give you the assistance you need. You can check another MG dealer in your area or you can order an interface for self diagnostics. The decision is yours .

 

[old fisherman]

TJA ?

 

[DonBattino452]

Traffic jam assistance?

 

[siteguru]

^^^ Yes ... like ACC (Adaptive Cruise Control) but also does steering. If you see a steering wheel symbol near the top-left of the driver screen then TJA is selected.

 

[Jamesrr]

^^^ Yes ... like ACC (Adaptive Cruise Control) but also does steering. If you see a steering wheel symbol near the top-left of the driver screen then TJA is selected.

Just to clarify.

In my experience the colour of the steering wheel (car in lane markings in ACC mode) is important to note.

If the wheel/lane markings is White, steering control (for both TJA or LKA/ELK in ACC) is inactive.

If Green, it is active.

If Yellow/Orange it is disabled, typically by virtue of turning off ELK in the system settings/pull down menu.

 

[DonBattino452]

Long press the left hot key button disables TJA, too . With R40 in my case...

 

[Jamesrr]

Long press the left hot key button disables TJA, too . With R40 in my case...

Isn't it easier to just tap the brakes?

I don't use TJA but use ACC extensively.

Does a long press of the left toggle disable TJA or just the steering function.

I'd love a "physical button" method to turn off LKA/ELK in ACC but retain the speed keeping/ distance keeping function ( the functionality I actually want).

 

[DonBattino452]

Sorry, I have to tell it more precisely: Long press switches between TJA and ACC mode.

About LKA/ELK: You can use Macrodroid and Keymapper to set a macro for this exact setup.

 

[double68]

Sorry, I have to tell it more precisely: Long press switches between TJA and ACC mode.

About LKA/ELK: You can use Macrodroid and Keymapper to set a macro for this exact setup.

Which versions of Macrodroid and Keymapper do you use?
I don't want to cause any damage.
Thanks

 

[DonBattino452]

Keymapper 4.0.0-beta.06-foss.apk
Macrodroid 5.0.2

You need access to the Android Subsystem. It's Android Automotive Operating System 9.

A little show case: Post #199 first video... Not mine

 

[ReintjeWA]

Isn't it easier to just tap the brakes?

I don't use TJA but use ACC extensively.

Does a long press of the left toggle disable TJA or just the steering function.

I'd love a "physical button" method to turn off LKA/ELK in ACC but retain the speed keeping/ distance keeping function ( the functionality I actually want).

It’s a good point you raise, depending on road conditions etc. TJA might be activated but not working because it can’t get the parameters it needs.

It’s strange that it is reported as working when the car is set to miles, but not when set to kms, which does indicate a fault of some kind to me. You’d think the dealership would try a re-install of the software maybe.

 

[siteguru]

Just to clarify.

In my experience the colour of the steering wheel (car in lane markings in ACC mode) is important to note.

And just clarify the clarification ... I didn't make any such statement to say TJA was Active, merely that the option was Selected. (As opposed to ACC, or speed limit mode, or none).

 

[Traxxx]

The TJA failed when the car was serviced at the end of November. Before that it only worked when hje car was set yo miles. I live in Spain so usually have it set too km.Now it does not work at all. My dealer looked at the car but said they could not do anything. Are there any fixes l can try at home rather than return to the dealer?
Love driving this car but anything to do with the computer seems a bit random!

I hope your Cruise Control/TJA has been fixed by your MG dealer though updating all the software modules. I had my MG4 serviced in November 2025 as well and updated the software modules but now my Cruise Control/TJA is DANGEROUS. If your dealer is not helping, contact MG directly and complain to them. With the latest update, my Cruise Control/TJA steers very close to other cars, does not sit in the centre of the lane, does not correct it's position with LKA (Lane Keep Assist), and requires strength to keep it from colliding with other cars. Very scary.