What it means
The control module monitors the exhaust-brake input signal and sets this code when it rises above the expected range. This indicates a high electrical input; the code alone does not identify the failed component.
At a glance
- Usually lights the check-engine light
How it works
The exhaust-brake input circuit carries the driver’s request to the control module. This code sets when the signal rises above its expected electrical range, which can make the module interpret the input as continuously active or invalid.
Common causes
Most likely first.
- Signal shorted to supply
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Exhaust-brake input may appear continuously active
- Exhaust brake may respond unexpectedly or fail to engage
How to diagnose it
- Check freeze-frame data and live input status to see whether the exhaust-brake request remains high with the driver control released.
- Inspect the input connector for corrosion, displaced pins, or contact with a supply source.
- Trace the signal and supply wiring for pinching or insulation damage where it could touch battery voltage or another powered circuit.
- Use the wiring diagram to test for a short to supply and verify the switch or sensor changes its output as intended.
- Compare input readings at the switch and module with the manufacturer’s specification to isolate the wiring or component fault.
Common fixes
- Repair a signal wire shorted to a supply or pinched against a powered wire.
- Reseat or repair corroded or displaced connector terminals.
- Replace a faulty exhaust-brake switch or input sensor if its output stays high when released.
- Repair damaged harness insulation and secure the wiring away from power sources.
Can I keep driving?
The exhaust brake may respond unexpectedly or fail to engage, so drive cautiously and avoid relying on it on steep descents. If it activates without a request, stop somewhere safe and arrange repair before continuing.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.