P0473 Code: Exhaust Pressure Sensor High – Causes, Symptoms & Fixes
The P0473 diagnostic trouble code is specific to diesel engines and signals that your vehicle’s exhaust pressure sensor has detected abnormally high pressure in the exhaust system. This code is monitored by your engine control module (ECM) to ensure proper operation of emissions control systems, particularly the diesel particulate filter (DPF) and exhaust aftertreatment systems. When pressure readings exceed the manufacturer’s threshold, your check engine light illuminates and this code is stored in memory.
What Does P0473 Mean?
P0473 stands for “Exhaust Pressure Sensor High.” The exhaust pressure sensor (also called a differential pressure sensor or DPF pressure sensor) measures the pressure difference across the diesel particulate filter. This sensor helps the engine control module monitor filter saturation and determine when regeneration is needed.
When the ECM detects that exhaust pressure readings are consistently higher than the calibrated maximum threshold—typically indicating excessive backpressure—it sets code P0473. This usually means:
- The DPF is heavily loaded with soot and needs regeneration or cleaning
- There’s a physical blockage in the exhaust system
- The exhaust pressure sensor itself is malfunctioning
- The sensor wiring or connector is corroded or damaged
- The ECM is not receiving proper sensor signals
This code is primarily found on diesel vehicles equipped with modern emissions systems, including Ford PowerStroke, Dodge Cummins, GM Duramax, and other diesel trucks and SUVs.
Common Symptoms
- Check Engine Light: Illuminated on the dashboard
- Reduced Engine Power: Limp mode activation to protect the engine
- Decreased Fuel Economy: Engine running less efficiently
- Excessive Smoke: Black or gray smoke from the exhaust
- Rough Idle: Engine may stumble or hesitate at idle
- Difficulty Starting: Engine cranks slowly or takes multiple attempts
- Loud Exhaust Noise: Unusual sounds from the exhaust system
- DPF Regeneration Issues: Frequent or failed regeneration attempts
- Reduced Power During Acceleration: Sluggish throttle response
- Burning Smell: Acrid or chemical odor from exhaust
Possible Causes (Ranked by Frequency)
1. Clogged or Saturated Diesel Particulate Filter (DPF)
The most common cause of P0473 is a DPF that has accumulated excessive soot and ash. When the filter becomes too full, backpressure rises dramatically, triggering the code. This typically occurs after 80,000–120,000 miles of operation or when the vehicle is driven primarily in stop-and-go city traffic rather than highway miles.
2. Exhaust System Blockage
Debris, rust, or physical obstructions in the exhaust piping downstream of the sensor can restrict exhaust flow and increase backpressure. This includes damaged mufflers, collapsed pipes, or foreign objects lodged in the system.
3. Faulty Exhaust Pressure Sensor
The sensor itself may fail electrically or mechanically, sending false high-pressure readings to the ECM. Sensor failure is more common in vehicles with high mileage or those exposed to extreme temperature cycling.
4. Corroded or Damaged Sensor Wiring
Water intrusion, salt exposure, or mechanical damage can corrode the sensor connector or wiring harness, causing intermittent or false signals. This is especially common in vehicles driven in winter conditions with road salt.
5. Exhaust Manifold or Turbo Issues
A cracked exhaust manifold, failed turbocharger, or turbo boost control problems can alter exhaust flow characteristics and pressure readings, triggering the code.
6. ECM Software or Calibration Issues
Rarely, outdated engine control module software or incorrect calibration parameters can cause the ECM to misinterpret sensor data and set a false P0473 code.
7. Failed DPF Regeneration
If the DPF regeneration process fails to complete properly, soot accumulates and pressure rises. This can result from fuel quality issues, engine problems, or sensor faults preventing successful regen cycles.
Diagnostic Steps
Step 1: Retrieve and Document the Code
Use an OBD-II scanner to read the P0473 code and any related codes (such as P0472 for low exhaust pressure). Note whether the code is active (current) or stored (historical). Check for freeze frame data showing engine load, RPM, and temperature when the code was triggered.
Step 2: Visual Inspection
Inspect the exhaust system for obvious damage, leaks, or blockages. Look for:
- Cracked or rusted exhaust pipes
- Loose or damaged muffler
- Soot buildup around exhaust outlet
- Visible damage to the DPF housing
Step 3: Check Sensor Wiring and Connectors
Locate the exhaust pressure sensor (typically mounted on or near the DPF) and inspect its connector for corrosion, moisture, or loose pins. Clean the connector with electrical contact cleaner and reseat it firmly. Check the wiring harness for cuts, abrasion, or pinches.
Step 4: Measure Sensor Voltage
With the engine off, use a digital multimeter to measure the reference voltage (typically 5V) at the sensor connector. With the engine running at idle, monitor the sensor output voltage. Compare readings to manufacturer specifications. Abnormal voltage readings suggest a faulty sensor.
Step 5: Perform a DPF Regeneration
Attempt a manual or passive DPF regeneration cycle using a professional diesel diagnostic scanner. If regeneration completes successfully and the code clears, the DPF may have simply been overloaded. If regeneration fails or the code returns, proceed to the next step.
Step 6: Check Exhaust Backpressure
Using a diesel diagnostic tool, measure actual exhaust backpressure at idle and under load. Compare to manufacturer specifications (typically 0–2 inches of water column at idle). Excessive backpressure confirms a blockage or DPF saturation issue.
Step 7: Inspect or Replace the DPF
If backpressure is high and regeneration has failed, the DPF likely needs cleaning or replacement. A professional shop can perform a forced regeneration or chemical cleaning. If the filter is damaged internally, replacement is necessary.
Step 8: Replace the Exhaust Pressure Sensor (if needed)
If sensor voltage readings are out of range or erratic, replace the sensor with a factory or OEM-equivalent part. Ensure proper installation and connector seating.
Step 9: Clear the Code and Test Drive
After repairs, clear the code using your scanner and perform a 20–30 minute test drive under varied conditions (highway, city, acceleration). Monitor for code return. If the code doesn’t return after 100+ miles, the repair was successful.
Repair Cost Estimates
The cost to repair a P0473 code varies significantly depending on the root cause:
- Sensor Replacement: $200–$600 (parts + labor) – Most affordable option if the sensor is faulty
- DPF Cleaning: $300–$800 – Chemical or thermal cleaning to remove soot without replacement
- DPF Replacement: $1,500–$4,000+ – Expensive but necessary if the filter is damaged or cleaning fails
- Wiring/Connector Repair: $100–$400 – Minimal cost if only electrical connections need repair
- Exhaust System Repair: $500–$2,000+ – Depends on the extent of damage and parts involved
- Turbocharger Service: $1,000–$3,000+ – If turbo issues are contributing to the problem
Average Total Cost: $600–$1,500 for most P0473 repairs, with DPF-related fixes being the most common and expensive scenario.
Can I Still Drive?
Severity: Moderate to High
Driving with code P0473 active is not recommended, though the vehicle may still be drivable in limp mode:
- Short-term: You can drive to a repair shop, but avoid extended highway driving or heavy loads
- Engine Damage Risk: Prolonged high exhaust backpressure can damage the turbocharger, exhaust valves, and engine internals
- Fuel Economy: Expect significantly reduced MPG and sluggish performance
- Emissions: The vehicle will fail emissions testing and may not be street-legal in some jurisdictions
- DPF Damage: Continued operation with a saturated DPF can cause permanent filter damage, requiring expensive replacement
Recommendation: Address this code promptly. Have the vehicle diagnosed by a qualified diesel technician within 24–48 hours to prevent further damage.
Frequently Asked Questions
Q: Can I clear the P0473 code myself without repairs?
A: Clearing the code without addressing the underlying cause will only temporarily hide the problem. The code will return within days or weeks. The ECM will continue monitoring exhaust pressure, and the fault condition will persist. Always diagnose and repair the root cause before clearing codes.
Q: What’s the difference between P0473 and P0472?
A: P0472 indicates exhaust pressure is too LOW, while P0473 indicates it’s too HIGH. P0472 often points to sensor failure or exhaust leaks, while P0473 typically indicates blockage or DPF saturation. Both codes require professional diagnosis, but the repair approaches differ significantly.
Q: Will a DPF cleaning fix P0473, or do I need replacement?
A: A professional DPF cleaning can resolve P0473 if the filter is simply saturated with soot and the filter itself is not damaged. However, if the filter has internal cracks, melted substrate, or ash buildup that won’t dissolve, replacement is necessary. A diagnostic scan and visual inspection can determine which approach is appropriate.
Q: How can I prevent P0473 from happening again?
A: Regular highway driving (allowing DPF regeneration), using quality diesel fuel, maintaining proper engine oil levels, and following the manufacturer’s service intervals are key. Avoid excessive idling, short trips, and towing beyond the vehicle’s capacity. Some owners use fuel additives designed to lower DPF ash content, though results vary.
Q: Is P0473 covered under warranty?
A: DPF and emissions components are typically covered under the manufacturer’s emissions warranty (often 8 years/80,000 miles or longer). However, coverage may be denied if the vehicle has been modified, neglected, or driven in ways that accelerated DPF saturation. Check your warranty documentation or contact the dealer for specifics.