What it means
Voltage on the sound generator B control line is below the expected window. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
At a glance
- Usually lights the check-engine light
How it works
Engine sound control B carries the control signal for the B channel of the sound generator. The module sets P26ED when it detects the circuit voltage below its expected range, which can leave that channel weak, silent, or erratic.
Common causes
Most likely first.
- Control wire shorted to ground
- Amplifier input stage short
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light may be on
- Engine sound enhancement may be reduced, absent, or irregular
- No change in normal engine operation may be noticeable
How to diagnose it
- Capture freeze-frame and live data for the B circuit, then see whether the low reading is present continuously or changes when the fault returns.
- Inspect the B-channel harness and connector for chafing to ground, moisture, corrosion, or a pushed-back terminal.
- With the circuit isolated as directed by the manufacturer, check the B control wire for a short to ground and test its continuity.
- Check connector terminal condition and voltage drop across the B circuit while the system is commanded on.
- If the wiring and terminals pass, test the amplifier B input stage and sound generator load using the manufacturer's diagnostic procedure.
Common fixes
- Dry and clean the B-channel connector and restore its terminal fit.
- Repair insulation where the B control wire is shorted to ground.
- Replace a damaged connector terminal or corroded connector.
- Replace the amplifier if its B input is confirmed shorted.
Can I keep driving?
This fault generally affects the enhanced sound from channel B rather than engine operation, so driving is usually possible if there are no other symptoms. Have it checked if other warnings appear or the vehicle's normal operation changes.
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.