P0471 – Exhaust Pressure Sensor Range/Performance

What Does Code P0471 Mean?

P0471 is a generic powertrain code that indicates the engine control module (ECM) has detected the exhaust pressure sensor signal is outside the expected range of operation. This sensor, also known as the exhaust back pressure (EBP) sensor, monitors pressure in the exhaust system to help optimize engine performance and emissions.

Urgency and Severity

When code P0471 is triggered, you can typically continue driving the vehicle in the short term as long as no serious drivability issues are present. However, it's best to have the problem diagnosed and repaired promptly to prevent potential damage to the exhaust system, turbocharger, or emissions components. If the check engine light is flashing or you experience a significant loss of power, it's recommended to stop driving and have the vehicle towed to a repair shop.

Applicability

Code P0471 is a generic code that applies to many makes and models, especially turbocharged gas and diesel engines. It's commonly seen on Ford trucks with the 6.0L Power Stroke diesel (2005+), Ford EcoBoost engines, Ram trucks with the 6.7L Cummins (2007+), Mercedes vehicles with the 3.0L V6 diesel (2007+), and Nissan trucks with the 3.0L Cummins V6 diesel (2015+). The specific troubleshooting steps may vary slightly between manufacturers.

Parts Involved

The main component related to code P0471 is the exhaust pressure sensor itself. This sensor is typically mounted on the exhaust manifold or turbocharger and connects to the ECM via a wiring harness. Its role is to provide a voltage signal to the ECM indicating exhaust back pressure levels. The ECM uses this data, along with inputs from other sensors, to adjust turbo boost, EGR flow, and other parameters.

Common Causes

Potential causes of a P0471 code include:

• Faulty exhaust pressure sensor
• Wiring issues in the exhaust pressure sensor circuit (shorts, opens, poor connections)
• Obstructed or leaking pressure sensor vacuum hose
• Leaks or restrictions in the exhaust system
• Malfunctioning EGR system
• Faulty ECM (rare)

Diagnosis Steps

1. Scan for all codes and document freeze frame data.
2. Visually inspect the exhaust pressure sensor, wiring, and vacuum hose for obvious faults.
3. Compare exhaust pressure sensor voltage to factory specifications using a digital multimeter or scan tool. At key-on, engine off (KOEO), the signal should match the barometric pressure (around 100 kPa or 14.7 psi at sea level).
4. If the KOEO reading is out of range, disconnect the sensor and recheck the signal. It should default to a fixed value around 50 kPa (7.3 psi). If not, suspect a wiring issue.
5. Inspect the exhaust system for leaks or restrictions, especially upstream of the sensor. Repair as needed.
6. Test the EGR system for proper operation. Clean or replace the EGR valve and passages if necessary.

Repair Solutions

• Replace the exhaust pressure sensor if faulty
• Repair damaged wiring or connectors in the sensor circuit
• Clean or replace obstructed pressure sensor vacuum lines
• Fix exhaust leaks and remove restrictions
• Service the EGR system as needed
• Reflash or replace the ECM if no other issues are found (rare)

Prevention and Costs

Proper maintenance of the exhaust and emissions systems can help prevent code P0471. This includes fixing exhaust leaks promptly, regularly cleaning the EGR system, and addressing other codes that may affect EBP sensor operation.

Typical repair costs for a P0471 code range from $80-$350 USD (€75-€330 EUR), depending on the root cause. An exhaust pressure sensor replacement usually runs around $75-$200 USD (€70-€190 EUR) for parts and 0.5-1 hour of labor. Wiring repairs are often less than $100 USD (€95 EUR), while more involved exhaust or emissions repairs can exceed $300 USD (€285 EUR).

Related Codes

Other codes that may appear alongside P0471 include:

• P0401 – Insufficient EGR flow
• P0402 – Excessive EGR flow
• P0470 – Exhaust pressure sensor malfunction
• P0472 – Exhaust pressure sensor low voltage
• P0473 – Exhaust pressure sensor high voltage
• P0474 – Exhaust pressure sensor intermittent

In summary, code P0471 indicates a range or performance issue with the exhaust pressure sensor. While not always an immediate threat, it's important to diagnose and repair this problem quickly to avoid damage to other components. Proper testing and a thorough inspection of the exhaust and emissions systems are key to an accurate diagnosis. With some know-how and the right tools, this is a problem that many DIYers can tackle at home.

Frequently Asked Questions About P0471

What does the P0471 code mean?

P0471 is a generic OBD-II code indicating an issue with the exhaust pressure sensor’s circuit range or performance.

How urgent is it to address a P0471 code?

While not immediately critical, it’s advisable to diagnose and repair the issue promptly to prevent potential damage to the exhaust system or turbocharger.

Can I continue driving with a P0471 code?

You can typically continue driving short-term if there are no drivability issues, but it’s best to have it checked soon.

What vehicles commonly experience the P0471 code?

It’s common in turbocharged engines, particularly in Ford, Ram, Mercedes, and Nissan diesel vehicles.

What are the main symptoms of a P0471 code?

Symptoms may include decreased fuel efficiency, lack of power when accelerating, and an illuminated check engine light.

What causes a P0471 code?

Common causes include a faulty exhaust pressure sensor, wiring issues, exhaust leaks, or a malfunctioning EGR system.

How is a P0471 code diagnosed?

Diagnosis typically involves scanning for codes, inspecting wiring and connections, and testing the exhaust pressure sensor.

Can I diagnose and fix a P0471 code myself?

With proper knowledge and tools, many DIYers can diagnose this issue, but professional help may be needed for complex cases.

What parts might need replacement to fix a P0471 code?

The exhaust pressure sensor, wiring harness, or vacuum lines may need replacement.

How much does it typically cost to repair a P0471 code?

Repair costs can range from $80 to $350 USD, depending on the root cause and labor rates.

Are there any related codes that often appear with P0471?

Yes, related codes include P0470, P0472, P0473, and P0474, all related to exhaust pressure sensor issues.

Can a P0471 code cause damage if left unaddressed?

While not immediately damaging, ignoring it could lead to reduced performance and potential damage to the exhaust system or turbocharger over time.

How does the exhaust pressure sensor work?

It monitors pressure in the exhaust system and sends a voltage signal to the ECM to help optimize engine performance and emissions.

Can a clogged catalytic converter cause a P0471 code?

While not a direct cause, a clogged catalytic converter can increase exhaust back pressure, potentially triggering this code.

How often should the exhaust pressure sensor be replaced?

There’s no set replacement interval. It should be replaced only when faulty or as part of diagnosing a P0471 code.

Can a P0471 code affect emissions testing?

Yes, this code can cause a vehicle to fail an emissions test as it indicates a potential issue with the exhaust system.

Is the exhaust pressure sensor the same as the MAP sensor?

No, they are different sensors. The MAP sensor measures intake manifold pressure, while the exhaust pressure sensor measures exhaust system pressure.

Can a P0471 code be caused by a software issue?

In rare cases, it could be caused by a PCM software issue. Updating the PCM software might resolve the problem.

How long does it typically take to diagnose and repair a P0471 code?

Diagnosis can take 1-2 hours, with repair time varying based on the issue. Simple sensor replacement might take an hour, while more complex repairs could take several hours.

Can aftermarket exhaust modifications trigger a P0471 code?

Yes, significant changes to the exhaust system can alter back pressure and potentially trigger this code.