P0243
Turbocharger Boost Sensor B Circuit High
Powertrain Fuel and Air Metering Turbocharger Boost Control 🟡 Moderate — Fix within a week
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What This Actually Means
In plain language — no jargon

Your turbocharger boost sensor B is sending a voltage signal that's too high, like a volume knob stuck at maximum. The engine computer can't properly control turbo boost pressure and may reduce performance or trigger limp mode.

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Symptoms You May Notice
3 known symptoms for this code
Reduced engine power or limp mode activation
Check Engine Light illuminated
Higher than normal boost pressure readings
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Embedded Systems Insight
What the ECU/ECM is actually computing

The ECU monitors the analog voltage output from the turbocharger boost sensor B circuit. This sensor measures manifold absolute pressure (MAP) and converts it to a voltage signal. The ECU expects this signal to stay within a normal operating range; when voltage exceeds the maximum threshold, it triggers the fault.

Voltage & Parameter Thresholds

Parameter Normal Range Fault Condition
Boost Sensor B Voltage 0.5V to 4.5V Above 4.7V or short-to-battery condition
Boost Pressure Range 0 to 30 PSI Sensor reads artificially high pressure
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Diagnostic & DIY Fix Guide
Check these in order — from cheapest to most complex
1
Boost sensor wiring harness
Inspect connector for corrosion, loose pins, or bent terminals and reseat or clean as needed.
2
Boost sensor B
Replace the sensor if voltage remains high after checking wiring; sensor may have internal short-to-battery condition.
3
Engine Control Module (ECM) software
Perform ECM reprogramming or reset if fault persists after sensor and wiring replacement.