Yukon Denali

Power Brake Units May Leak Fluid From Hydro-Boost Unit on GMC Yukon Denali

Problem Description and Possible Solution

Power brake systems using "hydro-boost" may leak power steering fluid from the hydro-boost unit located behind the brake master cylinder. Replacement of the hydro-boost unit is the common repair to correct this concern.

Problem Data
RepairPal Verified
Average mileage: 146,555 (94,000–229,000)
8 model years affected: 1999, 2000, 2002, 2003, more2004, 2005, 2006, 2007
19 people reported this problem
Viewing 1 - 7 of 7 comments
Power steering pump went out and then hydro boost starting leaking
leak at booster from power steering
Leaking behind master cylinder
hydroboost failure was triggering the Service Immediately lights and applying the brakes. replaced hydroboost for around $900 and it fixed it.
booster pump for power steering/brake leaking extensively. been advised to replace it
Thought the PS pump was leaking - replaced in my drive. Still had a hard to find leak. Took to good honest shop - diagnosed as the hydrobooster. Waiting on estimate now. See the part is available at O'reilly for about $106 - rebuilt. No sure this is a 'repair in my driveway' type of thing I could do. $584 with labor.
Once the breech occurred, almost impossible to make right turns and braking is EXTREMELY difficult.