Faulty exhaust pressure sensor B (internal failure or drift); Damaged, corroded, or disconnected wiring or connector at the sensor; Clogged or restricted exhaust pressure sensor tube or port; Exhaust leaks upstream of the sensor causing false pressure readings; Failed or contaminated sensor due to soot buildup; PCM software issue or internal fault (less common)

DTC codes / P04xx · Auxiliary emission controls / P047B

P047BExhaust Pressure Sensor B Circuit Range/Performance

Q: What does code P047B mean?

Exhaust Pressure Sensor B Circuit Range/Performance. P047B means the powertrain control module (PCM) has detected that the exhaust pressure sensor B circuit is reporting a signal outside its expected range or is not performing as designed. The PCM compares the sensor's voltage to what it expects under current engine operating conditions and sets this code when the signal is implausible or erratic.

P047B means the powertrain control module (PCM) has detected that the exhaust pressure sensor B circuit is reporting a signal outside its expected range or is not performing as designed. The PCM compares the sensor's voltage to what it expects under current engine operating conditions and sets this code when the signal is implausible or erratic.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaAuxiliary emission controls

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine power or limp mode in some vehicles
Poor fuel economy or rough running if the sensor is used for load calculations
Failed emissions test due to the stored code
In rare cases, a noticeable hesitation or surge during acceleration

Common causes, most likely first

Faulty exhaust pressure sensor B (internal failure or drift)
Damaged, corroded, or disconnected wiring or connector at the sensor
Clogged or restricted exhaust pressure sensor tube or port
Exhaust leaks upstream of the sensor causing false pressure readings
Failed or contaminated sensor due to soot buildup
PCM software issue or internal fault (less common)

How to diagnose and fix it

Inspect the sensor and its wiring for physical damage, corrosion, or loose connections
Check the sensor tube and port for blockage or soot buildup and clean if necessary
Perform a visual inspection for exhaust leaks near the sensor
Use a scan tool to monitor live sensor data and compare to expected values
Test the sensor circuit with a multimeter for proper voltage and ground
Replace the exhaust pressure sensor B if testing confirms it is faulty
Clear the code and verify the repair with a test drive

Common traps when diagnosing P047B

A clogged sensor tube is a frequent cause that mimics a failed sensor, so always check the tube before replacing parts.
Exhaust leaks upstream of the sensor can cause this code even when the sensor itself is good, so inspect the exhaust system carefully.
Some vehicles use exhaust pressure sensor B for EGR flow calculation, so a fault can affect EGR operation and set related codes.
The sensor may pass a static resistance test but still fail under operating conditions, so live data monitoring is essential.
After replacing the sensor, some vehicles require a relearn or adaptation procedure to avoid a repeat code.

Can I keep driving with P047B?

You can generally drive with this code if the engine runs normally, but avoid heavy acceleration or towing until it is repaired. If the engine enters limp mode or runs poorly, seek service promptly to prevent further damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.