What it means
Turbo speed sensor A signal voltage above the upper limit — short to reference voltage or open signal return.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Turbocharger or supercharger speed sensor A measures the forced-induction unit’s rotational speed. This code sets when sensor A’s signal is above the expected electrical range, which can happen if the signal is pulled toward its reference voltage or its return path is open.
Common causes
Most likely first.
- Signal wire shorted to reference voltage
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
Symptoms
- Check engine light
How to diagnose it
- Record freeze-frame data and check sensor A’s live speed reading for an implausibly high or fixed value.
- Inspect the speed sensor A connector and harness for corrosion, loose terminals, or wiring pinched against a power or reference source.
- Check sensor A’s ground and return path for an open or high-resistance connection.
- Use the wiring diagram to test the signal wire for a short to reference voltage and verify continuity through the harness.
- If wiring and return circuits meet the manufacturer’s specification, test sensor A for an internal high-output fault.
Common fixes
- Repair signal wiring shorted to the reference supply.
- Restore the sensor A return path and secure poor connector contacts.
- Replace damaged terminals or repair pinched harness insulation.
- Replace speed sensor A if its signal remains high with correct wiring.
Can I keep driving?
With only the check-engine light, a cautious trip to a repair location is generally reasonable. Avoid sustained boost or hard acceleration because the controller may receive a falsely high turbo or supercharger speed and manage the unit incorrectly.
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.