Turbocharger Boost Sensor B Circuit High
P0242 indicates the turbocharger/supercharger boost sensor B is reading a voltage signal that is too high, preventing the engine computer from accurately measuring boost pressure. The PCM will substitute a generic boost value and limit turbo boost and fuel timing, reducing engine performance and potentially causing catalytic converter damage if left unaddressed.
What You Might Notice
- Check engine light illuminated
- Reduced engine power and acceleration
- Poor fuel economy
- Black smoke from exhaust
- Turbocharger underperforming or no boost
Most Common Causes
- 1
Faulty boost sensor B
The sensor itself is malfunctioning and sending an incorrect high voltage signal to the PCM. This is the most direct cause of a high circuit voltage fault.
- 2
Wiring short to voltage
The sensor wiring harness has a short circuit or is touching a live power source, causing artificially high voltage readings on the sensor circuit.
- 3
Corroded or loose connector
Poor electrical connection at the sensor connector due to corrosion or inadequate seating can cause intermittent high voltage signals or circuit faults.
- 4
Faulty PCM or reference circuit
The engine control module itself may have a defective input circuit, or the 5-volt reference signal may be malfunctioning, causing false high readings from an otherwise good sensor.
How to Diagnose It
- 1
Check Faulty boost sensor B — The sensor itself is malfunctioning and sending an incorrect high voltage signal to the PCM. This is the most direct cause of a high circuit voltage fault.
- 2
Check Wiring short to voltage — The sensor wiring harness has a short circuit or is touching a live power source, causing artificially high voltage readings on the sensor circuit.
- 3
Check Corroded or loose connector — Poor electrical connection at the sensor connector due to corrosion or inadequate seating can cause intermittent high voltage signals or circuit faults.
- 4
Check Faulty PCM or reference circuit — The engine control module itself may have a defective input circuit, or the 5-volt reference signal may be malfunctioning, causing false high readings from an otherwise good sensor.
How to Fix It
- 1
Replace boost sensor B
Remove and replace the turbocharger/supercharger boost sensor B with a new OEM or quality aftermarket unit. Ensure proper installation and seating of the connector.
- 2
Inspect and repair wiring harness
Check the boost sensor wiring for cuts, abrasions, or shorts to power sources. Repair any damaged wiring or replace the entire harness if necessary. Ensure connectors are clean and making good contact.
- 3
Clean or replace connector
Disconnect the boost sensor and inspect the connector for corrosion or debris. Clean with electrical contact cleaner or replace the connector if severely corroded. Reconnect securely.
- 4
Have PCM tested or replaced
If sensor, wiring, and connectors test good, the PCM input circuit may be faulty. Have the module tested by a qualified technician or replaced if defective.
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