Turns out old brake fluid is way worse than I thought for ABS modules

I always figured brake fluid just needed swapping for pedal feel and moisture. Then I read a Bosch tech bulletin from 2023 that said old fluid with high copper content can actually eat the plastic valve seals inside ABS pumps. Found it on a forum thread about a 2015 Silverado that needed a $1,200 module replacement after 7 years of never flushing the fluid. Anyone else run into this or am I the only one who skipped flushes for too long?

2 comments

2 Comments

thea_mitchell2026d ago

Wait is this actually a thing or just some dealer scare tactic to sell flushes? I've run my trucks 100k+ miles on factory fluid with zero ABS issues and my neighbor's a mechanic who says he's never seen a module die from old fluid.

the_anthony25d ago

I've actually worked on a few of these trucks, and your neighbor's right that they won't always die, but old fluid can cause problems over time. The brake fluid absorbs moisture from the air, and after a few years that water can corrode the internal parts of the ABS module. I had a 2012 Silverado come in with a dead ABS pump, and the fluid looked like rusty tea when we drained it. Your 100k miles without issues just means you got lucky, not that it's a myth. Those flushes are cheap compared to replacing a seized up module, which can run you $800 or more. I'd say do it every 30k or so if you want to be safe but don't let a dealer scare you into paying $200 for it.