P0472 – Exhaust Pressure Sensor Low

P0472 is a diagnostic trouble code you’ll often see on turbocharged diesel engines, especially in trucks and larger SUVs. When this code sets, your engine computer is telling you it’s seeing an abnormally low signal from the exhaust back pressure sensor. That signal is important for controlling turbo boost, EGR flow, and overall engine efficiency. If you ignore it, you can end up with poor drivability, extra smoke, and even turbo or DPF issues. The good news: with a structured approach, you can usually track this down without replacing half the engine.

What Does P0472 Mean?

P0472 stands for “Exhaust Pressure Sensor A Circuit Low.” Your ECU (engine control unit) constantly monitors the exhaust back pressure sensor to know how much pressure is in the exhaust stream. This helps it manage turbocharger operation, EGR (exhaust gas recirculation), and emissions systems.

When the ECU sees a voltage signal from that sensor that’s lower than expected (often close to 0 volts) for a certain amount of time, it sets P0472. This usually points to a wiring or sensor issue, not a mechanical exhaust restriction by itself.

Quick Reference

  • Code: P0472 – Exhaust Pressure Sensor A Circuit Low
  • System: Exhaust / Turbo / EGR control
  • Typical causes: Faulty exhaust back pressure sensor, wiring issues, clogged sensor tube
  • Severity: Low to moderate, but can affect drivability and emissions
  • Common on: Turbo diesel pickups and vans (Ford Power Stroke, Ram Cummins, etc.)

Real-World Example / Field Notes

In the shop, I see P0472 most often on Ford Power Stroke diesels and Ram Cummins trucks that tow or idle a lot. A typical case: customer comes in with a check engine light, reduced power, and sometimes increased fuel consumption. Scan tool shows P0472 and maybe an EGR or turbo code. Many people jump straight to replacing the turbo or EGR valve. In reality, I usually find a plugged exhaust pressure sensor tube full of soot, or a sensor connector full of corrosion from road salt. Cleaning or replacing a $50–$150 sensor and tube often solves what looks like a big, expensive problem.

Symptoms of P0472

  • Check engine light on: The MIL/SES light will be illuminated and P0472 stored in memory.
  • Reduced power: You may feel a lack of power, especially under load or while towing, as the ECU limits turbo boost.
  • Poor fuel economy: Incorrect exhaust pressure data can cause inefficient fueling and timing.
  • Rough idle or hesitation: The engine may idle unevenly or stumble on acceleration.
  • Excessive smoke: Some vehicles may show more black smoke due to poor air-fuel control.
  • Harsh or frequent regens (diesel DPF): Incorrect exhaust readings can affect DPF regeneration strategy.
  • Related codes present: You might see EGR, turbo boost, or DPF efficiency codes along with P0472.

Common Causes of P0472

Most Common Causes

  • Faulty exhaust back pressure sensor: Internal failure, contamination, or moisture ingress causing low or no signal.
  • Clogged sensor tube/line: Soot and carbon buildup in the small metal or rubber tube between the exhaust and sensor.
  • Damaged wiring harness: Chafed, broken, or shorted wires causing low voltage or open circuit.
  • Corroded connector: Rust, green corrosion, or loose pins at the sensor plug reducing signal voltage.
  • Poor ground or 5V reference issue: Shared circuits with other sensors can drop the signal below expected range.

Less Common Causes

  • ECU internal fault: Rare, but a bad driver circuit in the engine computer can misread a good sensor.
  • Aftermarket tuning issues: Poorly written tunes can alter expected sensor ranges and trigger P0472.
  • Severe exhaust restrictions: While usually causing “range/performance” codes, odd pressure behavior can contribute to P0472.
  • Water intrusion in harness: On trucks used in deep water or heavy snow, moisture can track into the loom and affect voltage.

Diagnosis: Step-by-Step Guide

Tools you’ll want: A good scan tool (with live data and Mode $06 if possible), a digital multimeter, basic hand tools, and sometimes a low-pressure gauge. Access to wiring diagrams or service information for your specific vehicle is very helpful.

  1. Confirm the code: Scan the vehicle, record P0472 and any other stored or pending codes. Clear them and see if P0472 returns quickly.
  2. Visual inspection: Locate the exhaust back pressure sensor and its tube. Check for melted wiring, rub-through, loose connectors, or obvious damage.
  3. Inspect the sensor tube: Remove the tube/line from the sensor and exhaust. Look for heavy soot, carbon, or blockage. Clean or replace if restricted.
  4. Check connector condition: Unplug the sensor. Look for corrosion, bent pins, oil, or water. Clean and apply dielectric grease if needed.
  5. Verify 5V reference and ground: With the key on, use a multimeter at the connector to confirm you have a solid 5V reference and good ground per the wiring diagram.
  6. Measure sensor signal voltage: Back-probe the signal wire with key on, engine off. Typical reading is around 0.5–1.0V at rest. A flat 0V or near 0V reading points to a sensor or wiring issue.
  7. Check live data: On the scan tool, monitor exhaust back pressure at idle and when lightly revving. The value should change smoothly. If the scan data is stuck or unrealistically low, suspect the sensor or circuit.
  8. Wiggle test the harness: While monitoring live data, gently move the harness and connector. If readings drop out or jump, you likely have an intermittent wiring fault.
  9. Compare with barometric/boost data: Some ECUs compare exhaust pressure to barometric pressure and boost pressure. If exhaust pressure is always lower than it physically can be, that supports a P0472 diagnosis.
  10. Rule out ECU issues: If wiring, power, ground, and a known-good sensor all check out, an internal ECU fault or tuning problem becomes more likely.

Pro tip: On many diesels, if you see P0472 along with EGR and turbo codes, fix the exhaust pressure sensor issue first. The ECU uses that sensor to control both systems, so one bad input can trigger a cascade of “false” codes.

Possible Fixes & Repair Costs

Once you’ve confirmed the root cause, repairs for P0472 are usually straightforward. In many cases, you’re looking at cleaning or replacing the exhaust back pressure sensor and tube, or repairing a wiring fault. Typical repair costs at a shop range from about $100–$300 for cleaning and simple wiring repairs, up to $300–$600 if the sensor and tube need replacement. Costs vary based on vehicle make, labor rates in your area, parts availability, and how difficult it is to access the sensor on your specific engine.

  • Clean or replace sensor tube: Remove carbon and soot, or install a new tube/line if badly plugged or rusted.
  • Replace exhaust back pressure sensor: Install an OEM or high-quality aftermarket sensor and clear codes.
  • Repair wiring/connector: Solder and heat-shrink damaged wires, replace corroded terminals or pigtails.
  • Update or correct tuning: On tuned vehicles, reload a proper calibration or return to stock if necessary.
  • ECU replacement (rare): Only after confirming all other components are good; usually the most expensive option.

Can I Still Drive With P0472?

You can usually drive short-term with P0472, but it’s not ideal. Many vehicles will go into a mild “limp” mode, reducing power and limiting turbo boost to protect the engine and emissions system. Towing, heavy loads, or high-speed highway driving with this code active are not recommended. Continued driving with incorrect exhaust pressure data can lead to poor fuel economy, more soot buildup, and extra stress on the turbo and DPF. It’s best to diagnose and repair the issue as soon as you can.

What Happens If You Ignore P0472?

If you ignore P0472, you risk long-term problems like accelerated DPF plugging, increased EGR system deposits, and possible turbocharger issues due to incorrect boost and exhaust management. Over time, what started as a simple sensor or wiring repair can turn into expensive component replacements and more downtime.

Related Codes

  • P0474 – Exhaust Pressure Sensor Intermittent
  • P0473 – Exhaust Pressure Sensor High
  • P0471 – Exhaust Pressure Sensor Range/Performance
  • P0470 – Exhaust Pressure Sensor
  • P0469 – EVAP Purge Flow Sensor Circuit Intermittent
  • P0468 – EVAP Purge Flow Sensor Circuit High
  • P0467 – EVAP Purge Flow Sensor Circuit Low
  • P0466 – EVAP Purge Flow Sensor Circuit Range/Performance
  • P0465 – EVAP Purge Flow Sensor Circuit
  • P0464 – Fuel Level Sensor “A” Circuit Intermittent

Key Takeaways

  • P0472 means your ECU is seeing a low signal from the exhaust back pressure sensor.
  • Most causes are electrical or sensor-related: bad sensor, clogged tube, or wiring issues.
  • Symptoms include check engine light, reduced power, poor fuel economy, and sometimes extra smoke.
  • Diagnosis involves checking the tube, sensor power/ground, signal voltage, and scan tool data.
  • Repairs are usually affordable compared to major turbo or DPF work if you address the code early.

Vehicles Commonly Affected by P0472

P0472 shows up most often on modern turbo diesel vehicles that rely heavily on exhaust pressure data. You’ll commonly see it on Ford Power Stroke trucks (6.0L, 6.4L, 6.7L), Ram pickups with Cummins engines, and GM Duramax-equipped Chevy and GMC trucks. It can also appear on some diesel vans, cab-and-chassis work trucks, and certain European diesel cars and SUVs. Gasoline turbo engines with exhaust pressure monitoring can set this code as well, but it’s far more frequent in the diesel world.

FAQ

Can P0472 cause limp mode?

Yes. Many diesel ECUs will reduce power and limit turbo boost when P0472 is active to protect the engine and emissions components. You may notice sluggish acceleration and lower top speed until the fault is repaired and codes are cleared.

Is P0472 always caused by a bad sensor?

No. While the exhaust back pressure sensor is a common failure point, P0472 can also be caused by a clogged sensor tube, damaged wiring, poor grounds, or connector corrosion. Testing the circuit and inspecting the tube before replacing parts will save you money.

How do I know if the exhaust pressure sensor tube is clogged?

If you remove the tube and see heavy carbon buildup or can’t blow through it easily, it’s likely restricted. A clogged tube often causes slow or stuck readings on the scan tool, and cleaning or replacing it is a simple, effective fix.

Can I clear P0472 and keep driving if it goes away?

You can clear the code and see if it returns, but if the underlying issue is still there, P0472 will usually come back. If it reappears quickly, you should perform a proper diagnosis instead of repeatedly clearing it and hoping it goes away.

How serious is P0472 compared to other engine codes?

P0472 is generally moderate in severity. It’s not as immediately dangerous as low oil pressure or overheating, but it does affect engine management and emissions. Ignoring it can lead to more expensive problems down the road, so it’s worth addressing sooner rather than later.