EN

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

P0472 Code: Exhaust Pressure Sensor A Circuit Low

Exhaust backpressure sensor signal near zero volts: dead sensor, grounded wire or lost 5 V reference.

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 Circuit Low
System
Emission Controls · Powertrain
Safe to drive?
With caution
Typical repair cost
$30–$500
DIY difficulty
Moderate

An exhaust backpressure sensor puts out a signal voltage that rests at roughly one volt at atmospheric pressure on many designs and climbs as backpressure builds. A reading near zero volts is physically impossible for a working sensor, because exhaust pressure can't fall far below the air around the truck. So when the signal sits at the bottom of the range, the engine computer sets P0472 and stops trusting it. The cause is electrical: the sensor has failed, the signal wire touches ground, or the sensor has lost its 5 V supply. This code is seen most often on diesel pickups such as Ford's Power Stroke engines; on some other makes the same number may refer to a pressure sensor ahead of the particulate filter, so confirm which part your engine calls sensor A. It is different from P2453 to P2455, which cover the filter's differential pressure sensor.

Can I keep driving? The truck will usually run, but the computer switches to default values for turbo and EGR control and may cut power. Drive it lightly to a shop and don't tow until it's fixed.

How to read P0472

How to read P0472P10243724
  1. P Powertrain
  2. 0 Generic (SAE)
  3. 4 Auxiliary emission controls
  4. 72 Specific fault

Symptoms

  • Check engine light that comes on immediately after start-up
  • Exhaust pressure reading on a scan tool stuck at zero or at its minimum
  • Lower power and slower boost build-up
  • Other 5 V sensor codes set at the same time on some engines
  • Reduced power mode when towing or climbing

Possible causes

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

  1. Sensor failed internally with its output stuck low 30%
  2. Connector heat-damaged, corroded or partly unplugged after turbo or EGR work 24%
  3. Signal wire shorted to ground against the block, a bracket or the exhaust heat shield 18%
  4. 5 V supply to the sensor open or dragged down 16%
  5. Water in the connector after pressure washing the engine bay 7%
  6. Engine computer input fault 5%

Diagnosis step by step

Diagnostic flow: P04721Read the voltage, not just thepressure2Unplug and look at the sensor mount3Jumper test the wiring4Check the 5 V reference5Test the signal wire for a short6Replace and confirm at rest

  1. Read the voltage, not just the pressure

    Key on, engine off, display the exhaust pressure sensor voltage PID. Most sensors of this type sit near one volt at rest; a value close to 0 V confirms the fault is present right now and not just a stored history code.

    Tools: OBD-II scanner

  2. Unplug and look at the sensor mount

    Find the sensor on its bracket and follow its steel pressure tube back to the manifold. Check that the bracket wasn't bent against a hot part during earlier repairs, and look inside the connector for melted plastic, green crust or a pin pushed back.

    Tools: Flashlight

  3. Jumper test the wiring

    With the sensor unplugged and the key on, briefly bridge the harness signal pin to the 5 V reference pin with a fused jumper. The scan tool reading should jump to maximum. If it does, the wiring and computer work and the sensor is bad; if it stays low, the problem is in the harness.

    Tools: Multimeter, OBD-II scanner

  4. Check the 5 V reference

    Still unplugged, measure between the reference pin and ground: you should see about 5 V. Zero volts with other sensors also complaining means the shared reference is pulled down somewhere, and unplugging sensors on that circuit one at a time finds the culprit.

    Tools: Multimeter

  5. Test the signal wire for a short

    Disconnect the engine computer connector as the service information allows and measure from the sensor's signal wire to ground. Any continuity means the insulation is damaged; look where the harness crosses the valve cover, turbo pedestal or heat shields.

    Tools: Multimeter

  6. Replace and confirm at rest

    After replacing the sensor or repairing the wire, clear the code and check that with the engine off the exhaust reading matches barometric pressure. A short drive should then show it rising smoothly with load.

    Tools: OBD-II scanner

Where the parts are

Exhaust: catalytic converter and O2 sensors (Bank 1 / Bank 2) – P04721212345
Exhaust: catalytic converter and O2 sensors (Bank 1 / Bank 2)
  1. 1Upstream O2 sensor
  2. 2Catalytic converter
  3. 3Downstream O2 sensor
  4. 4Diesel particulate filter
  5. 5Turbocharger

Repair options & costs

RepairDIY?Estimated cost
Clean, dry and reseat the sensor connector Yes $30–$120
Replace exhaust pressure sensor Yes $120–$350
Repair signal wire shorted to ground No $100–$350
Find and repair dragged-down 5 V reference circuit No $150–$500

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

Notes by brand

Field data

Volkswagen 2 Jetta Sportwagen

Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.

Emissions / smog test impact

Depends

Heavier diesel pickups are exempt from OBD emissions tests in many states, so the impact depends on your state and the vehicle's rating. Where the truck is tested by plugging in, the check engine light for P0472 is a fail.

Frequently asked questions

How is P0472 different from P0471?

P0471 means the reading is electrically fine but doesn't make sense, often because the sensor tube is plugged or there's an exhaust leak. P0472 means the voltage itself is too low to be real, which points to the sensor or its wiring.

Why can't exhaust pressure read zero?

The sensor reads absolute pressure. Even with the engine off, it should show roughly the barometric pressure around the truck, so a signal at the very bottom of the range can only come from an electrical fault.

Could cleaning the tube fix P0472?

Unlikely. A plugged tube gives slow or wrong pressure readings, which is P0471 territory. P0472 is about voltage, so check the connector, wiring and sensor instead.

Several sensor codes appeared together. Is it the exhaust sensor?

Possibly, if its internal short is pulling down the reference. Unplug the exhaust pressure sensor with the key on and see if the other readings return to normal; if they do, the sensor is the one to replace.

Sources