What Does P047A Mean?
The ECM has detected a general circuit fault in the exhaust pressure sensor 'B' circuit. This secondary exhaust pressure sensor, typically located downstream of the DPF or turbocharger, is not providing a valid signal. The driver may notice a check engine light and potential derate of power, as the ECM cannot accurately monitor exhaust backpressure.
Common Causes
30%
Faulty exhaust pressure sensor 'B' with internal circuit failure
28%
Open or shorted wiring in the sensor circuit
22%
Corroded or damaged connector at the sensor due to exhaust heat and moisture exposure
12%
Blocked or kinked pressure sensing hose/tube to the sensor
8%
ECM internal fault on the sensor input circuit
Diagnostic Steps
1
Check exhaust pressure sensor 'B' live data PID — with engine off (KOEO), the sensor should read atmospheric pressure (approximately 0 kPa gauge or ~100 kPa absolute). A reading of 0V or 5V suggests an open or short.
2
Inspect the sensor connector for corrosion, melted plastic, or heat damage. Verify all three pins (5V reference, signal, ground) are making solid contact.
3
Measure the 5V reference supply at the sensor connector — should be 5.0V ±0.1V. Verify ground shows less than 0.1V. If reference is missing, check the shared 5V reference circuit for shorts.
4
If the sensor has a pressure hose/tube, verify it is clear by blowing through it gently. Inspect for kinks, cracks, or soot blockage at the exhaust port.
5
Substitute a known-good sensor or apply a known pressure with a hand vacuum/pressure pump and verify the signal voltage changes proportionally (typically 0.5V at 0 kPa to 4.5V at max range).
Estimated Repair Cost
$100 - $500
Parts + labor, varies by vehicle and location
The ECM has detected a general circuit fault in the exhaust pressure sensor 'B' circuit. This secondary exhaust pressure sensor, typically located downstream of the DPF or turbocharger, is not providing a valid signal. The driver may notice a check engine light and potential derate of power, as the ...
The most common cause of P047A (Exhaust Pressure Sensor "B" Circuit) is: Faulty exhaust pressure sensor 'B' with internal circuit failure
Typical repair costs for P047A range from $100 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive short distances. Without accurate exhaust pressure monitoring, the ECM may not properly manage DPF regeneration or turbo boost, which could lead to component damage over time. Repair within a week.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P047A to identify the root cause.
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Quick Info
Category
Powertrain
System
Exhaust / Emissions System
Difficulty
Type
Generic (SAE)
Recommended Tools
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