The P0473 diagnostic trouble code (DTC) indicates a problem with the exhaust pressure sensor. This code signals that the engine control unit (ECU) has detected an abnormally high voltage reading from the exhaust pressure sensor, suggesting a potential issue within the sensor itself, the associated wiring, or the ECU. Understanding the causes and symptoms of this code is crucial for proper diagnosis and repair to ensure optimal engine performance and prevent potential damage.
The exhaust pressure sensor plays a vital role in monitoring the pressure within the exhaust system, particularly in diesel engines equipped with particulate filters (DPF). This information is critical for the ECU to regulate fuel injection, exhaust gas recirculation (EGR), and DPF regeneration processes. A faulty sensor reading can lead to decreased fuel efficiency, reduced engine power, and even damage to the DPF.
P0473: Exhaust Pressure Sensor High - Comprehensive Overview
| Category | Description | Potential Impact |
|---|---|---|
| Definition | Exhaust Pressure Sensor High Input. This DTC indicates that the engine control unit (ECU) has detected a voltage signal from the exhaust pressure sensor that is higher than the expected or normal operating range. | Reduced engine performance, decreased fuel efficiency, potential DPF damage, inability to initiate DPF regeneration, increased emissions, check engine light illumination. |
| Common Symptoms | Check Engine Light is illuminated, Reduced engine power, Poor fuel economy, Black smoke from exhaust, Hesitation during acceleration, Failure of DPF regeneration. | Driving experience negatively affected, increased running costs, potential for long-term engine damage if the issue is ignored. |
| Possible Causes | Short to voltage in the sensor signal circuit, Faulty exhaust pressure sensor, Open circuit in the sensor ground circuit, Corroded or damaged wiring harness, Exhaust leak near the sensor, Blocked exhaust pressure sensor port, ECU failure (rare). | Difficulty in diagnosing the root cause if multiple issues are present, potential for misdiagnosis and unnecessary repairs. |
| Diagnostic Steps | Verify the code with a scan tool, Inspect the exhaust pressure sensor and its wiring harness for damage, Check the sensor voltage with a multimeter, Perform a sensor test using a scan tool, Check for exhaust leaks, Inspect the exhaust pressure sensor port for blockage, Check the sensor ground circuit, Test the sensor signal circuit for a short to voltage, Replace sensor and retest, Consult a vehicle-specific repair manual. | Accurate diagnosis is crucial to ensure the correct repair is performed, saving time and money. Following a systematic approach minimizes the risk of overlooking potential causes. |
| Related Codes | P0470 (Exhaust Pressure Sensor Circuit Malfunction), P0471 (Exhaust Pressure Sensor Range/Performance), P0472 (Exhaust Pressure Sensor Low). | Understanding related codes can provide valuable context and assist in pinpointing the specific issue. |
| Sensor Location | Typically located in the exhaust system, either before or after the Diesel Particulate Filter (DPF), or near the turbocharger. The exact location varies depending on the vehicle make and model. | Knowing the sensor location is essential for visual inspection and testing. Consult a vehicle-specific repair manual for accurate location information. |
| Testing Procedures | Use a digital multimeter to measure the voltage at the sensor signal wire with the key on, engine off. Compare the reading to the manufacturer's specifications. Also, check the sensor ground circuit for proper continuity. Use a scan tool to monitor the sensor readings while the engine is running. | Accurate testing requires the use of appropriate tools and adherence to manufacturer's specifications. |
| Repair Strategies | Repair or replace damaged wiring, Replace the faulty exhaust pressure sensor, Clear the DTCs and retest the system, Address any exhaust leaks, Clean the exhaust pressure sensor port, Replace ECU (rare). | Choosing the correct repair strategy depends on the accurate diagnosis of the problem. Verify the repair by clearing the DTCs and retesting the system. |
Detailed Explanations
Definition: P0473 (Exhaust Pressure Sensor High Input) indicates that the ECU has registered a higher-than-expected voltage signal from the exhaust pressure sensor. This means the voltage reading from the sensor is outside the normal operating range specified by the vehicle manufacturer. The ECU interprets this abnormal signal as a potential fault within the sensor, its wiring, or the ECU itself.
Common Symptoms: Several symptoms can accompany the P0473 code. The most common is the illumination of the Check Engine Light (CEL). Other symptoms include reduced engine power, poor fuel economy, and black smoke emanating from the exhaust. You might also experience hesitation during acceleration and a failure of the DPF regeneration process, especially in diesel vehicles.
Possible Causes: A short to voltage in the sensor signal circuit is a frequent culprit. This means the sensor wire is making unintended contact with a voltage source. A faulty exhaust pressure sensor itself is another possibility, as internal failure can lead to inaccurate readings. An open circuit in the sensor ground circuit prevents the sensor from grounding properly, leading to incorrect voltage signals. Corroded or damaged wiring harnesses can also cause shorts or open circuits. An exhaust leak near the sensor can disrupt the pressure readings. A blocked exhaust pressure sensor port prevents the sensor from accurately measuring exhaust pressure. Finally, although rare, an ECU failure can also trigger this code.
Diagnostic Steps: Start by verifying the code with a scan tool to confirm its presence. Next, inspect the exhaust pressure sensor and its wiring harness for any visible damage, such as cuts, frayed wires, or corrosion. Check the sensor voltage with a multimeter to compare it to the manufacturer's specifications. Perform a sensor test using a scan tool, if available, to assess the sensor's functionality. Check for exhaust leaks near the sensor, as these can affect the pressure readings. Inspect the exhaust pressure sensor port for blockage, as debris can accumulate and impede accurate measurement. Check the sensor ground circuit for proper continuity. Test the sensor signal circuit for a short to voltage. If all else fails, replace the sensor and retest the system. Consult a vehicle-specific repair manual for detailed diagnostic procedures and specifications.
Related Codes: Understanding related codes can aid in diagnosis. P0470 (Exhaust Pressure Sensor Circuit Malfunction) indicates a general problem with the sensor circuit. P0471 (Exhaust Pressure Sensor Range/Performance) suggests the sensor's readings are outside the expected range or not performing as expected. P0472 (Exhaust Pressure Sensor Low) indicates a voltage signal that is lower than the expected range.
Sensor Location: The exhaust pressure sensor's location varies depending on the vehicle make and model, but it's typically located in the exhaust system. It may be positioned before or after the Diesel Particulate Filter (DPF) in diesel vehicles, or near the turbocharger. Consult a vehicle-specific repair manual for the exact location.
Testing Procedures: Use a digital multimeter to measure the voltage at the sensor signal wire with the key on and the engine off. Compare this reading to the manufacturer's specifications. Also, check the sensor ground circuit for proper continuity. A good ground should have very low resistance (close to 0 ohms). Use a scan tool to monitor the sensor readings while the engine is running and observe how the pressure changes with engine speed and load.
Repair Strategies: Begin by repairing or replacing any damaged wiring found during the inspection. If the sensor is deemed faulty, replace the exhaust pressure sensor with a new one. Clear the DTCs and retest the system after any repairs to ensure the problem is resolved. Address any exhaust leaks identified during the diagnostic process. Clean the exhaust pressure sensor port if it is blocked. Replacing the ECU is a rare occurrence and should only be considered after all other possibilities have been ruled out.
Frequently Asked Questions
What does the P0473 code mean? The P0473 code indicates that the engine control unit (ECU) has detected a higher-than-normal voltage signal from the exhaust pressure sensor. This suggests a problem with the sensor, its wiring, or the ECU.
What are the common symptoms of a P0473 code? Common symptoms include the check engine light, reduced engine power, poor fuel economy, and black smoke from the exhaust. The DPF regeneration might also fail in diesel vehicles.
What are the possible causes of the P0473 code? Possible causes include a short to voltage in the sensor signal circuit, a faulty exhaust pressure sensor, or damaged wiring. Exhaust leaks and a blocked sensor port can also trigger this code.
How do I diagnose a P0473 code? Use a scan tool to verify the code, inspect the sensor and wiring, check the sensor voltage with a multimeter, and look for exhaust leaks. A vehicle-specific repair manual will be helpful.
Can I fix a P0473 code myself? If you have experience with automotive repair, you can attempt to diagnose and fix the issue, but a professional mechanic is recommended for complex problems. Accurate diagnosis is crucial.
Conclusion
The P0473 code signals a high voltage reading from the exhaust pressure sensor, indicating a potential issue with the sensor, its wiring, or the ECU. Thorough diagnosis and proper repair are essential to restore optimal engine performance and prevent potential damage to the exhaust system, especially the DPF in diesel vehicles.