P0240
Turbocharger Boost Sensor B Malfunction
Powertrain Fuel and Air Metering Turbo Boost Control 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

The engine's turbo boost pressure sensor B is sending an invalid signal or out-of-range reading to the computer. Think of it like a faulty tire pressure gauge that gives wildly incorrect readings.

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Symptoms You May Notice
3 known symptoms for this code
Check Engine Light illuminated
Reduced engine power and turbo boost response
Rough idle or hesitation during acceleration
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors voltage output from the boost sensor B to determine actual manifold pressure for turbo control and fuel injection timing. The sensor should produce a voltage proportional to boost pressure (typically 0.5-4.5V). If the signal is stuck, erratic, or outside expected range, the ECU cannot properly regulate boost and fuel delivery.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Sensor Voltage Output 0.5V to 4.5V (proportional to boost pressure) Below 0.5V, above 4.5V, or no signal change
Boost Pressure Logic Sensor voltage matches expected boost under load Voltage does not correlate with engine load or remains static
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Electrical connector at boost sensor B
Inspect and reseat the sensor connector to ensure clean contact and proper seating.
2
Wiring harness to sensor B
Check for pinched, corroded, or damaged wires between ECU and sensor; repair or replace as needed.
3
Turbocharger boost sensor B
Replace the sensor if voltage remains out of range after connector and wiring checks.