P047D - Exhaust Pressure Sensor B - Circuit High
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P047D is a generic OBD-II diagnostic trouble code indicating that the Engine Control Module (ECM) has detected a voltage signal from Exhaust Pressure Sensor 'B' that exceeds the calibrated limit (typically above 4.8V). The sensor is a piezo-resistive device measuring exhaust backpressure, crucial for EGR flow calculation and VGT (Variable Geometry Turbo) control. A 'Circuit High' condition usually signifies an open circuit on the ground side, a short to voltage (5V reference or 12V), or internal sensor failure. The ECU may trigger a limp mode to prevent turbocharger overspeeding or DPF damage.
Possible Causes
Faulty exhaust pressure sensor (internal failure)
Wiring harness damage or poor connection (open circuit on the ground wire)
Signal wire shorted to voltage (5V or 12V)
Faulty Engine Control Module (ECM)
Symptoms
Recommended Solution
Workflow
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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