What is the difference between P0470 and P0471?

P0470 is an outright circuit malfunction (no signal or completely wrong voltage). P0471 means the sensor is working but its readings are implausible — typically a blocked pipe or borderline sensor.

It is moderate severity. It disrupts DPF regeneration which, if left long term, can lead to a blocked DPF and costly repair.

Can a blocked DPF cause P0471?

Yes. Excessive exhaust back pressure from a blocked DPF pushes the sensor reading out of the expected performance range, triggering P0471.

How do I clear the exhaust pressure sensor pipe?

Disconnect the pipe from both ends and blow through it with compressed air or a tyre pump. On heavily sooted pipes, a thin wire or pipe cleaner can help dislodge blockages.

How long does it take to fix P0471?

If the pipe is simply blocked, clearing it takes 10–15 minutes. Sensor replacement takes under an hour. DPF-related causes require more investigation and potentially a forced regeneration.

Does P0471 come on after a DPF clean?

It can, temporarily, as the ECU recalibrates to the new pressure readings. If it persists after a couple of warm-up cycles, the sensor or pipe needs attention.

P0471 — Fault Code | Mr Auto Fixer

What Is P0471?

P0471 is a range or performance fault from the exhaust back-pressure sensor. Unlike P0470 (which flags an outright malfunction), P0471 means the sensor is producing a signal but it is not changing as expected — the reading is implausible for the current engine operating conditions.

This is common on high-mileage diesel vehicles where the pressure pipe becomes partially blocked with soot, causing a sluggish or stuck reading. A failing sensor or high exhaust back pressure from a blocked DPF can also trigger this code.

Common Symptoms

Engine management light on
DPF warning light or failure to regenerate
Possible limp mode on some vehicles
Slight increase in fuel consumption
EGR operation may be affected

Common Causes

Partially blocked exhaust pressure sensor pipe (soot accumulation — very common)

Failing exhaust back-pressure sensor giving slow or frozen readings

High exhaust back pressure from a blocked or failing DPF

Damaged sensor wiring causing intermittent signal

Air leak in the exhaust system affecting pressure readings

Failed EGR valve altering exhaust pressure beyond expected range

How to Diagnose P0471

Clear the Pressure Pipe First

Disconnect the thin rubber or plastic pipe from the exhaust back-pressure sensor. Blow through it — any restriction indicates a soot blockage. Clear it with compressed air. This fixes P0471 in a large proportion of cases.

Live Data Check

Connect an OBD scanner and check exhaust pressure sensor live data. Blip the throttle — the reading should rise and fall immediately. A frozen or slow-responding value points to a blocked pipe or failed sensor.

Check DPF Differential Pressure

A blocked DPF creates abnormally high exhaust back pressure. If a DPF pressure drop test shows excessive restriction, the DPF needs cleaning or replacement — a new sensor will not cure the fault.

Inspect Sensor Connector

Check for corrosion or damaged pins at the sensor connector. Intermittent contact can produce implausible readings that trigger P0471.

Replace Sensor if Needed

If the pipe is clear and live data still shows a frozen or implausible reading, the sensor element has failed internally. Replace the sensor, clear the code, and test drive.

TipP0471 very frequently returns on the same vehicle if the root cause (blocked DPF or blocked pressure pipe) is not addressed. Simply clearing the code without investigating why back pressure is abnormal will result in the fault coming back within weeks.

Verdict

The number-one fix for P0471 is clearing the soot-blocked pressure pipe. If that does not cure it, check DPF condition before condemning the sensor.

P0471 — Fault Code