Turbocharger/Supercharger Boost Sensor A Circuit High

What it means

The engine computer has detected that the signal voltage from boost pressure sensor A is above its maximum allowed value. The usual cause is an open sensor ground or a signal wire shorted to a voltage source, so the computer reads a false high pressure and cuts turbo boost for protection.

Related codes: P0235P0237P0236P0234

Symptoms4

• Check engine light on.
• Loss of power and limp mode.
• Slow acceleration because the computer believes boost is already high.
• The fault may come and go with vibration or heat.

Possible causes5

• Open sensor ground wire or a corroded ground terminal in the connector.
• Short between the signal wire and the reference voltage wire or another voltage source.
• Moisture or oil inside the connector causing current leakage.
• Internal sensor failure.
• Engine computer fault (rare).

How to diagnose5

1. Watch the boost reading on a scan tool with the engine off; a reading far above barometric pressure confirms the fault.
2. Measure the voltage drop on the ground wire between the sensor and the computer.
3. Unplug the sensor and watch the signal; if it stays high, the wire is shorted to a voltage source.
4. Inspect the connector for moisture, oil or corrosion.
5. Wiggle the wiring while watching to catch an intermittent fault.

How to fix5

1. Clean and dry the connector or replace it.
2. Repair the open or corroded ground wire.
3. Separate the shorted wires and re-insulate them.
4. Replace the boost pressure sensor if it is proven faulty.
5. Clear the codes, then test under load and confirm the code does not return.

Repair cost

In Saudi riyals; the highlighted part is the expected range for this fault.

The cost is low for a ground or connector repair and reaches the upper end when the boost pressure sensor is replaced.

Prices are rough estimates for common cars at independent workshops and vary with the car and the source of the part.
Prices last updated: September 2026

Frequently asked questions