C0021 Brake Booster Performance code after replacing booster

I recently replaced the power brake booster, brake booster vacuum sensor, brake light switch, and air pump. After completing this I did a brake flush and bled all of the calipers. I am still getting a stiff brake pedal and a C0021 code. After replacing the brake booster with a second new unit there was no improvement.

While on the test drive after the second brake booster I got a U0414 code and the car started acting sluggish. Car seems to be in limp home mode and the transmission refused to let me shift it using the auto-stick, but I confirmed that the 4WD is still functional. After letting it sit for an hour that has gone away.

I have replaced everything in the power braking system minus the master cylinder so I don't really know where to go from here. Thank you!

*Edit* Before replacing the parts I had the C0021 code and the stiff brake pedal. I replaced the vacuum pump and brake booster at that time problem was solved minus the brake light switch but after replacing that everything worked. It then gave a code for the yaw rate sensor so I also replaced that. Then the car was down for a bit for a failed head gasket so after finishing that job the brake issues returned.

2014 Wrangler Unlimited Sahara 3.6

Mopar said:

What were the issues BEFORE you replaced the parts?

By stiff pedal you mean no power boost?

I’d be looking at the vacuum lines and check valves for a vacuum leak.

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Before replacing the parts i had the c0021 code and the stiff brake pedal. I replaced the vacuum pump and brake booster at that time problem was solved minus the brake light switch but after replacing that everything worked. It then gave a code for the yaw rate sensor so I also replaced that. Then the car was down for a bit for a failed head gasket so after finishing that job the brake issues returned.

I believe the stiff pedal means no power boost but this is my first time dealing with brake stuff. When I push the pedal not much happens and it feels like the pedal is pulsing. It is also quite hard to push the pedal.

I checked all of the vacuum lines for leaks and none of them seem to be leaking. I forgot to mention that the T fitting that connects the vacuum pump, brake booster check valve, and intake manifold broke when removing it. I picked up a new one at autozone and added hose clamps to make sure it wouldn't leak.

pc1p said:

Clogged booster vacuum hose or broken nipple at the intake manifold possibly?

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I can try to clear out the hoses with the air compressor, but the nipple at the intake manifold seems to be attached and not broken.