Jimny ABS Warning: Brake Booster Sensor Issues

I had a very similar issue with my 2002 Grand Vitara diesel last year. As someone with moderate experience in car maintenance, the symptoms you describe match exactly what I encountered. The weak braking performance combined with ABS system errors initially had me worried about the brake booster, but it turned out the system just needed proper bleeding. After consulting with my workshop, they found air bubbles in the hydraulic brakes causing inconsistent pressure readings. The fix involved a complete brake fluid flush and proper bleeding sequence using professional diagnostic tools. Total cost was 90€ including new brake fluid. Vehicle safety was restored completely after this service. A few questions to better assist you: Have you noticed any changes in brake pedal feel (spongy, hard, or inconsistent)? When did the ABS warning light first appear? Can you share the specific error codes from your diagnostic scan? Has there been any recent brake work performed on the vehicle? This information would help determine if your issue matches what I experienced or if you might be dealing with a different problem.

Latest service at 175375 KM shows this was more complex than initially thought. After getting it checked, my ABS issue was actually caused by a faulty wheel speed sensor, not the brake booster as suspected. The brake pedal response improved significantly after replacing the sensor and clearing the error codes. The hydraulic brakes were also serviced during the repair since the brake fluid was quite old. Total repair cost was 280€ including parts and labor. The ABS system now works perfectly with no warning lights. Based on the detailed diagnosis, would recommend checking both the wheel speed sensors and brake fluid condition before replacing the brake booster sensor.

Thanks for the update about your Jimny repair. Your findings really help explain what was going on with my Grand Vitara too. After my initial brake fluid service, I actually had the same issue return a few months later. The workshop did a more thorough check and found a faulty wheel speed sensor was the root cause, just like in your case. The pressure sensor readings were incorrect because the ABS system was getting bad data from that wheel speed sensor. Once we got the sensor replaced and the hydraulic brakes properly serviced, the brake performance returned to normal and all error codes cleared. The repair cost on my vehicle was slightly higher at 320€, but it included a full brake fluid flush and new sensor. Most importantly, the ABS system has been working flawlessly since then. Your experience confirms that thorough diagnostics are crucial, sometimes the obvious solution isnt the correct one. This is a good reminder to always get a complete system check with proper diagnostic tools rather than just replacing parts based on initial symptoms.

Thanks everyone for the helpful feedback. Really glad I asked here before jumping to conclusions about the brake booster pressure sensor. Getting the wheel speed sensor replaced along with fresh brake fluid made a huge difference in how the ABS system performs. For anyone searching with similar issues: make sure to get proper diagnostic tools readings before replacing parts. In my case, what seemed like a brake booster problem was actually a faulty wheel speed sensor affecting vehicle safety. The complete repair including parts and labor came to 280€, which was less than expected for the improvement in braking performance. Will update the forum if any other issues come up, but for now, the Jimny is running perfectly with no warning lights or error codes. Thanks again for helping diagnose this correctly and saving me from unnecessary replacement parts costs.