Faulty exhaust pressure sensor reading out of range high; Damaged, chafed or heat-affected wiring causing a short to the supply voltage or signal line; Corroded, loose or contaminated connector terminals at the sensor or control unit; Open circuit in the sensor ground wire, giving a high signal reading; Blocked, split or disconnected sensor pressure pipe or sooted sensing port (where fitted); Genuinely high exhaust back pressure from a restricted exhaust, filter or turbine problem; Fault inside the engine control unit or an outdated calibration known to affect this sensor's diagnostics.

P047D

Exhaust Pressure Sensor B Circuit High.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
4: AreaAuxiliary emission controls
7D: FaultThe specific fault in that area

What it means

P047D is a generic powertrain code meaning the engine control unit has detected a high voltage signal from exhaust pressure sensor 'B' circuit. The signal is above the expected range, which usually points to a short to voltage, an open ground or sensor reference fault, or a failed sensor. Which sensor is 'B' (for example a bank 2 sensor, or one located before or after a turbocharger or particulate filter) depends on the vehicle and engine.

Symptoms

Engine management light on
Reduced power or limp mode
Turbocharger boost control behaving poorly or boost limited
Poor throttle response or hesitation
Particulate filter or exhaust aftertreatment warnings on some diesel models
Possible rough running or increased smoke

Possible causes

Faulty exhaust pressure sensor reading out of range highlikely
Damaged, chafed or heat-affected wiring causing a short to the supply voltage or signal linelikely
Corroded, loose or contaminated connector terminals at the sensor or control unitlikely
Open circuit in the sensor ground wire, giving a high signal readingpossible
Blocked, split or disconnected sensor pressure pipe or sooted sensing port (where fitted)possible
Genuinely high exhaust back pressure from a restricted exhaust, filter or turbine problempossible
Fault inside the engine control unit or an outdated calibration known to affect this sensor's diagnosticsrare

How to diagnose

Read all stored and pending codes plus freeze frame data, and note whether other exhaust pressure, boost or filter codes are present.
Check manufacturer information to identify which sensor is 'B' on this model and engine, and where it is fitted.
Visually inspect the sensor, its pipe (if fitted), wiring and connector for heat damage, chafing, corrosion, soot blockage or loose fit.
With the engine off and then running, view live exhaust pressure data and compare it with ambient pressure at key-on and with expected values at idle and under load.
Unplug the sensor and check the reference supply, ground and signal wires for correct voltage, continuity and shorts to supply or ground, following the wiring diagram.
Check for any real restriction by inspecting the exhaust, particulate filter data, turbocharger and any pressure pipes for blockage or leaks.
If the wiring tests good, substitute-test or replace the sensor and see whether the reading and code clear.
Check for relevant technical bulletins or calibration updates for the model before suspecting the control unit.

How to fix

Replace the exhaust pressure sensor if it is faulty or reading incorrectly.
Repair or replace damaged wiring, and clean or renew corroded connector terminals.
Restore a good sensor ground or reference supply if either is open or shorted.
Clean or replace blocked or damaged sensor pressure pipes and fix any exhaust leaks around the sensor.
Repair the underlying exhaust restriction, such as a blocked filter or turbo fault, if back pressure is genuinely high.
Update the control unit calibration only if the manufacturer lists it as a known fix for this fault.

Can I keep driving?

Medium severity

The car can usually be driven for a short time, but power may be reduced and the underlying fault could affect the turbo or exhaust aftertreatment. Get it diagnosed soon, and stop driving if there is a severe loss of power, heavy smoke or warning lights flashing.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.