P2588: Turbocharger Boost Control Position Sensor B Circuit Low
What to do
The engine will feel flat and may go into reduced power. It is not usually damaging, so getting it to a workshop is fine.
Ask for the wiring to be inspected before the sensor is replaced. This loom lives beside a turbocharger housing that runs red hot, and on a twin-turbo engine there are two of them in a crowded bay — heat-damaged insulation is one of the commonest findings, and a new sensor on a damaged loom fails the same way.
Worth mentioning: if the other turbocharger's position sensor has also set a code, say so. Two at once usually means a shared power or earth wire rather than two failed sensors, which is a much smaller repair.
What this code means
The second turbocharger's vane position circuit reads below its valid range — a short to ground, a failed reference supply, or a sensor that has dropped to the bottom of its scale.
The module loses closed-loop control of that turbocharger and defaults its vanes to a safe position, so boost falls away.
Heat is the reason this circuit fails more often than most, and on a twin-turbo installation there is more of it. Two turbine housings running red hot in one engine bay leave less room and less air between hot metal and the looms routed past it, so insulation hardens faster and chafes sooner than the same part would on a single-turbo engine. Wiring damage is a leading cause here rather than an afterthought.
One check is worth doing before the sensor is condemned: read the A-side codes as well. A shared reference supply or a common ground feeding both sensors will take both down, and two position codes at once point at the supply rather than at either sensor. That is a cheap thing to establish and it prevents two sensors being replaced to fix one wire.
Likely causes
Start here
- Wiring shorted to ground · moderate
- Heat damage to sensor or wiring · moderate
- Faulty turbocharger vane position sensor · moderate
Less common
- Corroded or loose connector · easy
- Failed sensor reference voltage supply · moderate
Symptoms
Components involved
Information, not instruction
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