P2595: Turbocharger Speed Sensor B Circuit Low
What to do
The engine will feel down on power. That is the module protecting the turbocharger because it cannot tell how fast it is spinning, so driving gently to a workshop is fine.
Ask for the wiring to be inspected before the sensor is replaced — this loom runs against a housing carrying exhaust gas and is among the hottest on the vehicle.
And mention it if the other turbocharger's speed sensor has set a code as well. Two at once usually means a shared power or earth wire rather than two failed sensors, and that is a far cheaper fix than replacing both.
What this code means
The second turbocharger's speed circuit reads below its valid range — a short to ground, a failed reference supply, or a sensor producing nothing where a signal is expected.
As at P2580, a reported zero is only impossible in context: a turbocharger genuinely is stationary with the engine off, so the module judges the reading against what the engine is doing and sets this code when a zero cannot be true. On a sequential system that context is narrower, because the second turbocharger legitimately turns slowly until the changeover brings it in — so the module has fewer conditions in which a zero is provably wrong, and the code often appears only after sustained higher-speed driving.
One check is worth doing before the sensor is condemned: read the A-side codes too. Both speed sensors are commonly fed from a shared reference supply and a common ground, and a failure there takes both down at once. Two speed codes together point at the supply rather than at two sensors, which is a much smaller repair than it first appears.
Without a usable signal the module caps boost protectively, so the engine feels flat.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Heat damage to sensor or wiring · moderate
- Faulty turbocharger speed sensor · moderate
Less common
- Failed sensor reference voltage supply · moderate
- Corroded or loose connector · easy
Symptoms
Components involved
Information, not instruction
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Community experience
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