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Error Code P0473 is defined as Exhaust Pressure Sensor High. This means there’s an electrical problem in the exhaust system back pressure sensor circuit or burned/frayed wiring.
This code is a generic trouble code, meaning it applies to all vehicles equipped with variable nozzle turbochargers (both gasoline and diesel engines). This started around 2005 on Ford trucks equipped with 6.0L diesel engines, all Ford EcoBoost engines, and eventually to Cummins 6.7L in 2007, Mercedes lineup with 3.0L engines in 2007 and the Cummins 3.0L 6 cyl in Nissan pickups starting in 2015. This code also applies to some VW vehicles models.
Error Code P0473 is identified as an electrical problem related to the exhaust system back pressure sensor circuit and often associated with Error Codes P0471 and P0472.
This code takes place when the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) detects an irregular voltage reading from the exhaust system back pressure sensor circuit. This abnormal reading of voltage could be caused by either too low or too high voltage. Exhaust pressure is usually monitored in diesel and turbocharged gasoline engines.
Other related error codes include:
- Error Code P0470 Exhaust Pressure Sensor “A” Circuit
- Error Code P0471 Exhaust Pressure Sensor “A” Circuit Range/Performance
- Error Code P0472 Exhaust Pressure Sensor “A” Circuit Low
- Error Code P0474 Exhaust Pressure Sensor “A” Circuit Intermittent
As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory system. Other common symptoms include:
- Engine lacks power
- Manual regeneration will be impossible
- Eventually, the problem can lead to crank-no start as well
- A crank-no start (if a perform regeneration isn’t able to perform)
Different causes for this code include:
- Open in ground circuit that leads to exhaust pressure sensor
- Open in signal circuit in between PCM and exhaust pressure sensor
- Short voltage in signal circuit exhaust pressure sensor
- Faulty exhaust pressure sensor – internally shorted to voltage
- Defective PCM (rare)
How to Check
In many cases, a simple PCM reprogram can do the trick, and usually the first step for diagnosis for this code.
Next, mechanics check the exhaust pressure sensor and see if wires and connectors look fine and completely intact. They will also clean these parts if needed.
If the code is not caused by a physical problem, then mechanics should use a scan tool to clear the error code P0473 and other related codes from memory. The vehicle is then checked to see if the code comes back.
If the code does NOT come back, then there’s a good chance the fault is caused by a faulty connector.
If the code comes back, on the other hand, the sensor associated with the circuit must be tested.
Both the PCM and exhaust pressure sensor must be checked if all other tests are passed.
How to Fix
Common repairs for this code include:
- Repair or replacement of exhaust leaks
- Cleaning, repair or replacement of damaged connectors or wirings
- After repairs, the codes must be cleared, and the vehicle must be taken for a test drive to see if it returns
Burned or frayed wiring on the engine is never a good thing. Thus, if you have this code, your vehicle must be immediately checked. While the problem can be a minor issue for the moment, it can lead to serious problems and expensive repairs in the future. Also, this code means the vehicle may stop from working while driving, which can be extremely dangerous.