EN

Severity: Moderate Code type: Generic (all makes) ✱

P0471 Code: Exhaust Pressure Sensor A Range/Performance

The exhaust backpressure reading doesn't match what the computer expects; the sensor tube is often plugged.

Unverified: this manufacturer-specific definition comes from a single source or varies by model. Confirm it with a brand-specific scan tool.

At a glance

Severity: 3/5 – Moderate3/5

Severity: Moderate

Meaning
Exhaust Pressure Sensor A Range/Performance
System
Emission Controls · Powertrain
Safe to drive?
With caution
Typical repair cost
$60–$1,500
DIY difficulty
Moderate

Many turbo diesels, most famously Ford's 6.0L and 6.4L Power Stroke and other heavy-duty pickup engines, measure exhaust backpressure ahead of the turbo with a sensor mounted away from the heat and connected to the manifold by a small steel tube. The engine computer uses that reading to steer the variable-geometry turbo and the EGR valve. P0471 sets when the reading is electrically fine but implausible: with the engine off it doesn't match barometric pressure, or under load it doesn't rise as it should. A soot-plugged tube, a leaking fitting or an exhaust leak upstream of the sensor are the usual reasons. Which sensor carries the 'A' label varies by manufacturer, and some makers use this code for a pressure sensor ahead of the particulate filter, so the exact meaning should be confirmed for your engine.

Can I keep driving? Drivable with care. Turbo and EGR control may be degraded, which can cause low power, overboost protection or excessive smoke; avoid towing and long climbs until the reading is trustworthy again.

How to read P0471

How to read P0471P10243714
  1. P Powertrain
  2. 0 Generic (SAE)
  3. 4 Auxiliary emission controls
  4. 71 Specific fault

Symptoms

  • Low power or sluggish turbo response, especially when towing
  • Check engine light, sometimes with underboost or EGR flow codes
  • More black smoke under acceleration
  • Turbo whistle or chuff from an exhaust leak near the manifold
  • Reduced power mode on some trucks

Possible causes

Ranked by how often each cause is behind this code (editorial estimate).

  1. Sensor tube or port plugged with soot, so the sensor sees a delayed or damped pressure 32%
  2. Exhaust leak between the engine and the sensor port (manifold gasket, up-pipe, cracked flange) 20%
  3. Sensor drifted internally and no longer reads correct pressure 18%
  4. Cracked or loose sensor tube or fitting 12%
  5. Sticking turbo vanes or EGR valve making real backpressure abnormal 12%
  6. Engine computer software needing an update 6%

Diagnosis step by step

Diagnostic flow: P04711Compare with barometric pressure2Watch the reading rise with rpm3Inspect and clear the sensor tube4Look for exhaust leaks upstream5Check turbo vane and EGR behavior6Replace the sensor if it fails therest test

  1. Compare with barometric pressure

    Key on, engine off, read exhaust pressure, barometric pressure and manifold pressure on a scan tool. On a healthy system all three agree closely, typically within about half a psi. An exhaust reading that is clearly off at rest points to the sensor itself.

    Tools: OBD-II scanner

  2. Watch the reading rise with rpm

    At warm idle, exhaust pressure should read slightly above barometric; a steady run at around 2,500 to 3,000 rpm should make it climb smoothly. A reading that hardly moves or lags seconds behind the rpm change is typical of a plugged tube.

    Tools: OBD-II scanner

  3. Inspect and clear the sensor tube

    Disconnect the tube at the sensor and at the manifold and check it's open end to end. Hard soot can often be cleared with a wire; a tube that is cracked, collapsed or corroded at the nut should be replaced. Never blow compressed air into the sensor itself.

    Tools: Flashlight, Pliers

  4. Look for exhaust leaks upstream

    Listen for ticking or chuffing at the manifolds and turbo inlet during a cold start, and look for soot trails at flanges and gaskets. A leak before the sensor port bleeds off pressure and makes the reading low under load.

    Tools: Flashlight, Smoke machine

  5. Check turbo vane and EGR behavior

    With a scan tool, command the turbo vane control and EGR valve while watching exhaust pressure. Pressure should respond right away; if it doesn't, vanes stuck with soot or an EGR valve that won't close may be causing a real, not a sensor, problem.

    Tools: OBD-II scanner

  6. Replace the sensor if it fails the rest test

    If the tube is clear, there are no leaks and the reading still disagrees with barometric pressure at rest, replace the sensor. Clear the codes and repeat the idle and rpm checks to confirm.

    Tools: OBD-II scanner

Where the parts are

Air intake and fuel metering – P047112345678
Air intake and fuel metering
  1. 1MAF sensor
  2. 2Turbocharger
  3. 3Throttle body
  4. 4Intake manifold
  5. 5Fuel injector
  6. 6EGR valve
  7. 7Fuel pump
  8. 8Thermostat

Repair options & costs

RepairDIY?Estimated cost
Clean or replace exhaust pressure sensor tube Yes $60–$250
Replace exhaust backpressure sensor Yes $120–$350
Repair exhaust manifold gasket or up-pipe leak No $300–$1,200
Clean or repair sticking variable-geometry turbo No $400–$1,500
Clean or replace EGR valve No $250–$800

Rough US estimates for parts and labor; shop rates vary by region. Not a quote.

Notes by brand

Ford

On the 6.0L Power Stroke, a soot-clogged exhaust backpressure sensor tube is a well-known cause of this code and of poor turbo response. Clearing or replacing the tube is often the whole repair, and leaking up-pipes are the next thing technicians check.

Emissions / smog test impact

Depends

Many states exempt heavier diesel pickups from OBD emissions testing, so whether P0471 matters depends on the vehicle's weight rating and your state. Where the truck is OBD-tested, the lit check engine light fails it.

Frequently asked questions

Is P0471 the same as the DPF pressure sensor code?

Usually not. P2452 to P2455 cover the particulate filter differential pressure sensor. P0471 normally concerns a separate exhaust backpressure sensor before the turbo, although some manufacturers do use it for a sensor near the filter.

Can I clean the sensor tube myself?

On most trucks, yes. The tube unscrews at both ends; clearing the soot and refitting with a little anti-seize on the manifold end often fixes the code. Don't push anything into the sensor port.

Why does an exhaust leak cause a sensor code?

The sensor measures the pressure at its port. A leak upstream lets pressure escape, so under load the reading stays lower than the computer's model predicts, and it flags the reading as implausible.

Will P0471 hurt the engine?

Not directly, but turbo and EGR control rely on this reading. Running for a long time with bad data can mean overboost protection, poor EGR control and more soot, so it's worth fixing promptly.

Sources