help me with DTC code U0121 code and spongy brake problem 2010 JK Wrangler

my 2010 jeep wrangler unlimited with code U0121 only present
sometimes when hitting a bump it gives 3 light in dash stabilitrak abs and parking brake all light up then goes after 2 - 10 seconds any tips to start with?
thanks and best regards
i uploaded a snapshot photo for the code thanks

check your abs lines one may be damaged, it's easy to check the lines

jeeeep said:

check your abs lines one may be damaged, it's easy to check the lines

Click to expand...

do you mean abs sensors and connector? or oil lines ?

Ali said:

do you mean abs sensors and connector? or oil lines ?

Click to expand...

the sensor and connectors - they're the black plastic lines going behind the brakes usually tied to the brake line and have rubber grommets on them

you'll need to remove your wheels to see them behind the brake lines.

this mentions it and shows what the line looks like, it doesn't discuss changing it out but if you do a search on Jeep JK ABS Speed sensor you'll find several articles on replacing it.

after looking up codes, may also be an issue with the PCM, you'll have to take it to the dealer for that.