C0299-5A Service Brakes Soon

[gregsmy]

I have a somewhat random "Service Brakes Soon" that shows on the dash. I recently purchased a bi directional scan tool to help figure this out. The code I get is the C0299-5A "Brake boost regulation pressure sensor plausibility failure". I replaced the sensor a year or so back with the same issue and it went away for a while. Its mostly random that it happens with the exception of after work. Almost every day at the the exact same place the "service brakes soon" message will pop up. I clear it with the top button and its good on the rest of the drive home. Its after the truck has been running for about 10 minutes and I am just leaving work. I get down the road a few miles driving around 60-65 mph with light to no acceleration. The brakes work normally not requiring any extra effort. I used my scan tool to record some data of the vacuum and just as I start to leave, the vacuum starts to drop according to the sensor. It slowly clicks down to the point it trips the sensor and the SBS message pops up. It continues to show very low vacuum even when I am stopping to make a turn (brakes feel fine and work normally). Then about 10 minutes later it starts to slowly click back up to the normal range. I have replaced the o-ring between the mc and booster. I also checked the vacuum hose from the booster to manifold and it looks good. It sure seems like the sensor has gone bad again but I wonder why? It's like a $60 part, so I dont want to just replace it if it could be something else. Any help would be appreciated. If there is other data that I should be looking at please let me know.

 

[Doubeleive]

I have a somewhat random "Service Brakes Soon" that shows on the dash. I recently purchased a bi directional scan tool to help figure this out. The code I get is the C0299-5A "Brake boost regulation pressure sensor plausibility failure". I replaced the sensor a year or so back with the same issue and it went away for a while. Its mostly random that it happens with the exception of after work. Almost every day at the the exact same place the "service brakes soon" message will pop up. I clear it with the top button and its good on the rest of the drive home. Its after the truck has been running for about 10 minutes and I am just leaving work. I get down the road a few miles driving around 60-65 mph with light to no acceleration. The brakes work normally not requiring any extra effort. I used my scan tool to record some data of the vacuum and just as I start to leave, the vacuum starts to drop according to the sensor. It slowly clicks down to the point it trips the sensor and the SBS message pops up. It continues to show very low vacuum even when I am stopping to make a turn (brakes feel fine and work normally). Then about 10 minutes later it starts to slowly click back up to the normal range. I have replaced the o-ring between the mc and booster. I also checked the vacuum hose from the booster to manifold and it looks good. It sure seems like the sensor has gone bad again but I wonder why? It's like a $60 part, so I dont want to just replace it if it could be something else. Any help would be appreciated. If there is other data that I should be looking at please let me know.

this one? if so there may be a way to test it, maybe a ohm test

Brake Fluid Pressure Sensor BST115 For Chevrolet Avalanche Silverado GMC Sierra | eBay

Brake Fluid Pressure Sensor. Pressure Sensor. Nitrogen Oxides (NOx) Sensor. Nox Sensor. Tire Pressure Sensors. Tire Pressure Monitor Sensors. Fuel Pressure Sensors. Oil Pressure Sensors.

www.ebay.com

 

[gregsmy]

this one? if so there may be a way to test it, maybe a ohm test

Brake Fluid Pressure Sensor BST115 For Chevrolet Avalanche Silverado GMC Sierra | eBay

Brake Fluid Pressure Sensor. Pressure Sensor. Nitrogen Oxides (NOx) Sensor. Nox Sensor. Tire Pressure Sensors. Tire Pressure Monitor Sensors. Fuel Pressure Sensors. Oil Pressure Sensors.

www.ebay.com

No. It’s the vacuum sensor that goes into the brake booster. Like the old style check valve but with a sensor built in.

 

[Doubeleive]

No. It’s the vacuum sensor that goes into the brake booster. Like the old style check valve but with a sensor built in.

there should be a way to test it then either with a meter or a vaccum tester