P0473 Fault Code

Long Description

Fault code P0473 is logged when the vehicle’s primary computer, the powertrain control module (PCM), has detected an issue with the back pressure exhaust system.

This happens when the PCM receives a voltage signal from the exhaust system back pressure sensor circuit that is higher than the allowable limit.

The back pressure sensor is typically fitted only to vehicles with turbocharger systems. This is done to allow the PCM to monitor the amount of pressure in the exhaust, the turbocharger, and the cylinders.

This data is used to optimize the turbocharger operation by controlling the turbocharger wastegate and the corresponding boost pressure.

Only vehicles with turbocharged engines are able to have fault code P0473 logged. However, there are a lot of turbocharged cars nowadays. Audi is one of the most commonly reported when it comes to this issue, along with Volkswagen and Hyundai.

Other Signs of This Problem

Because of the importance of the back pressure sensor circuit in terms of proper turbocharger operation, fault code P0473 can come with some very noticeable symptoms.

The first and most obvious is the presence of the Check Engine light.

It is also very likely that the vehicle will enter limp mode as the turbocharger cannot function without back pressure sensor data.

If the vehicle does not enter limp or failsafe mode, the performance will be significantly diminished. The most obvious factor will be very low power output. This happens as the PCM uses a default value for the back pressure.

It is also possible for the vehicle to not run at all to prevent damage.

There may be other back pressure sensor fault codes logged like P0470, P0471, and P0472.

What Could Be The Problem?

As the fault lies with the back pressure sensor itself, it is likely that the potential causes are all electrical in nature. However, there are additional factors that can cause this.

One of the most likely causes is a blockage in the back pressure tube. This is where the back pressure sensor reads its pressure from. A blockage here will cause an excessive increase in pressure.

Another possibility is that the back pressure sensor is faulty. Additionally, the circuit components like wiring and connections may also be faulty or damaged.

While very unlikely, it is possible for an issue with the PCM to cause this code. There will likely be other fault codes logged if this is the issue though.

Fixes

Due to the electrical nature of the potential causes for fault P0473, it is likely that the fixes will also be electrical in nature.

However, one of the first steps to take is mechanical. This is to clear the back pressure tube. Any blockages must be removed.

The back pressure sensor should be tested. If it is faulty, it needs to be replaced.

Any damaged or frayed wires or loose connections in the back pressure sensor circuit need to be fixed.

A faulty PCM must be replaced.

Seriousness

Fault code P0473 is a serious problem. It can completely disable the turbocharger system in a vehicle, hugely decreasing performance.

In most cases, the vehicle will not be able to run outside of limp mode, rendering it almost useless.

It is strongly recommended this issue is resolved immediately.