What it means
The turbocharger speed sensor B circuit signal is below the expected range. The cause may be in the sensor, wiring, connector, or circuit supply.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Turbocharger speed sensor B sends the engine control module a signal used to track turbo speed. This code sets when that signal is below the expected range, which can happen if the signal wire is shorted to ground, corrosion adds resistance, or the harness is damaged; it is distinct from a high-signal fault.
Common causes
Most likely first.
- Signal wire shorted to ground
- Connector pins corroded - high contact resistance
- Harness chafing through insulation
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
How to diagnose it
- Review freeze-frame and live data for sensor B to confirm the low reading and the conditions when it occurs.
- Inspect sensor B's connector and turbo-area harness for corrosion, chafing through insulation, or loose terminals.
- Check for a signal wire short to ground, following the manufacturer's circuit test procedure.
- Test the sensor supply, ground, and signal path for excessive resistance or damage against the manufacturer's specification.
- If the circuit checks pass, test sensor B and inspect its target or reluctor for damage.
Common fixes
- Clean corrosion from the sensor B connector and repair damaged terminals.
- Repair a signal wire shorted to ground or chafed through its insulation.
- Repair a poor connection or damaged supply wire identified by circuit testing.
- Replace sensor B if it produces a low signal despite a verified circuit and correct installation.
Can I keep driving?
A low sensor B signal can disrupt turbo monitoring and boost control, with possible power loss or limp mode. Avoid heavy acceleration and stop if severe power loss, smoke, or unusual turbo noise occurs.
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.