C0021 on Jeep

Brake booster performance or signal fault (Dodge and Jeep)

Severity: Inspect soon

Owners on Dodge and Jeep vehicles report a stiff pedal or lost brake assist with this code, so the braking effort changes.

It gets more serious if:

Stop: Stop and have it towed if the brake pedal goes hard or sinks, or the brake warning light and a brake system failure message show.

Safety-critical system: explanation only, no DIY steps. Source: how we rate severity

This page covers only what differs on Jeep. For what C0021 means, the ranked causes and the test order, see the C0021 guide.

What's different on Jeep

Jeep

2012 · Grand Cherokee
Supported by vehicle data
An owner reports the dealer reading C0021-02 as brake booster general signal failure after a brake booster recall.

Sources and review

NHTSA complaint ODI 11491725: 2012 Jeep Grand Cherokee brake booster — NHTSA Office of Defects Investigation
NHTSA complaint ODI 11716853: 2014 Dodge Durango brake booster message — NHTSA Office of Defects Investigation
NHTSA complaint ODI 11689771: 2023 Jeep Grand Wagoneer no brakes — NHTSA Office of Defects Investigation

Last reviewed: October 15, 2026
Written by: Saurabh K.
Editorial review: Pending
Technician review: Technician review pending

This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error