P0473 — Exhaust Pressure Sensor “A” Circuit High #

Note: The description for DTC P0473 may vary depending on the vehicle manufacturer (OEM).

• Ford: Exhaust Pressure Sensor “A” Circuit High
• GM/Chevrolet: Exhaust Back Pressure Sensor Circuit High Voltage
• Chrysler: Exhaust Pressure Sensor Circuit High Input
• Mercedes-Benz: Exhaust Gas Pressure Sensor “A” High Signal
• Volkswagen/Audi: Exhaust Pressure Sensor 1 Signal too High

Summary of Code P0473 #

DTC P0473 indicates that the engine control module (ECM — the computer managing engine functions) has detected a voltage signal from the Exhaust Pressure Sensor “A” that is higher than the expected range. This sensor monitors exhaust pressure, typically before or after the diesel particulate filter (DPF), and helps the ECM regulate emissions and turbocharger performance. A “circuit high” alert usually means the sensor or its wiring is sending a higher voltage than normal, which can disrupt emissions control and engine performance. Addressing this code promptly is crucial, as persistent issues may lead to drivability problems or further component damage.

Common Symptoms for Code P0473 #

Drivers may experience a variety of symptoms when P0473 is active. These can range from subtle changes in engine behavior to more obvious warning lights on the dashboard. Common symptoms include:

• Illuminated Check Engine Light (CEL)
• Reduced engine power, especially under load
• Poor acceleration or turbo lag
• Increased smoke from the exhaust (especially on diesels)
• Regeneration issues with the Diesel Particulate Filter (DPF)
• Decreased fuel efficiency
• Engine may enter “limp” or “safe” mode

Probable Causes for P0473 (in order of likelihood) #

Several factors can trigger a high circuit signal from the exhaust pressure sensor. The most frequent causes are:

1. Faulty exhaust pressure sensor (sensor internal failure or contamination)
2. Short to voltage in the sensor’s signal wire (wiring insulation damage or harness issue)
3. Corroded or loose sensor connector
4. Blocked or damaged pressure hose leading to the sensor (common in diesel setups)
5. Faulty ECM (rare, but possible if all else checks out)

Step-by-Step Diagnosis for P0473 #

A methodical approach helps pinpoint the root cause of P0473. Here’s how a professional technician or an experienced DIYer would tackle it:

1. Verify the code with a scan tool and note any related codes (especially for DPF, turbo, or EGR systems).
2. Inspect the exhaust pressure sensor and its wiring for visible damage, corrosion, or loose connections.
3. Check the sensor’s reference voltage and ground circuits with a digital multimeter. Compare readings to OEM specifications.
4. Test the signal wire for shorts to voltage or ground (look for pinched or melted wires).
5. Examine the pressure hose/tube (if equipped) for blockages, disconnections, or leaks.
6. Substitute the sensor with a known good unit if possible to confirm sensor failure.
7. Clear the code and perform a road test to see if the code returns.
8. If unresolved, consider ECM evaluation or reprogramming as a last resort.

Possible Repairs for P0473 #

Once the root cause is found, repairs are typically straightforward. Common solutions include:

• Replace the exhaust pressure sensor if faulty or contaminated.
• Repair or replace damaged wiring or connectors between the ECM and sensor.
• Clean or replace the sensor’s pressure hose if blocked or leaking.
• Secure loose connectors and ensure all electrical terminals are corrosion-free.
• Reflash or replace the ECM only if all other repairs fail and diagnostics confirm a controller issue.

Can You Drive with Code P0473? #

Driving with P0473 is not recommended beyond short distances. While the vehicle may still run, a faulty exhaust pressure sensor can lead to improper turbo operation, excessive exhaust emissions, and even force the engine into limp mode, greatly reducing power. Prolonged driving can cause further damage, especially to emission control components like the DPF or EGR valve. Address the code as soon as possible to maintain safe operation and prevent costly repairs.

Vehicles Most Commonly Affected by P0473 #

P0473 appears most often in modern diesel vehicles, especially those equipped with advanced emission control systems. Commonly affected models include:

• Ford Super Duty trucks (F-250, F-350, F-450) with Power Stroke diesel engines
• Chevrolet Silverado and GMC Sierra Duramax diesels
• Dodge Ram 2500/3500 with Cummins diesel
• Mercedes-Benz Sprinter vans (diesel variants)
• Volkswagen/Audi TDI models
• Some late-model passenger cars with turbocharged gasoline engines (less frequent)

Common Mistakes & Best Practices for P0473 #

Avoiding misdiagnosis can save time and money. Here are frequent pitfalls and expert tips:

• Replacing the sensor without checking wiring — damaged wires or connectors often cause the fault.
• Overlooking pressure hose blockages — soot or condensation can clog lines to the sensor, especially on diesels.
• Ignoring other related codes — multiple codes may indicate a broader emission system issue.
• Skipping ECM ground checks — poor grounding can skew sensor signals.
• Always clear codes after repair and road test to confirm the fix.

Express FAQ: P0473 Answers at a Glance #

Still have questions? Here are clear, quick answers to the most common P0473 concerns:

• Q: Can a dirty sensor trigger P0473?
  A: Yes. Contamination from soot, oil, or moisture can cause false high readings and trip the code.
• Q: Is a generic OBD-II scanner enough for diagnosis?
  A: Usually, yes — but advanced scan tools that show live data make it easier to monitor sensor voltage and pinpoint wiring faults.