P0170 Fault Code

Long Description

Fault code P0170 is logged when the powertrain control module (PCM) has detected a malfunction in the fuel trim.

Fuel trim is the term used to describe the controlling of the air-fuel mixture that enters the combustion chambers of the engine. This ratio needs to be at 14.7 parts of air per every 1 part of fuel.

This is done by the PCM for a variety of reasons. These range from optimizing performance to reducing emissions.

This fault code is possible for any manufacturer, but brands like Hyundai, Nissan, and Opel/Vauxhall are some of the most commonly searched when it comes to this fault code.

Other Signs of This Problem

There are a number of noticeable symptoms that will present themselves if there is an issue with the fuel trim. These can range in severity depending on how bad the malfunction is.

The most obvious sign is the Check Engine light being illuminated along with the P0170 being immediately diagnosed from an OBD2 reader.

The vehicle’s performance will also degrade. This can include a loss of power, stumbling, and decreased fuel economy. The engine may also stall unexpectedly.

There may also be damage visible with the catalytic converter if the code has been logged for a substantial amount of time.

Similarly, if the engine is running rich, this can cause black smoke to be emitted from the exhaust system.

There may also be other fuel trim fault codes like P0171 and P0172. These can indicate that the fuel trim is running lean or rich respectively.

What Could Be The Problem?

There are several possible causes when it comes to fuel trim malfunctions. These can be found in the air intake, vacuum, or the fuel system typically. Essentially, any upstream system that helps determine the air-fuel mixture could be at fault.

One of the simplest causes is old or contaminated engine oil.

A dirty or faulty mass airflow (MAF) sensor can also cause lead to this issue.

A fault in the fuel system can lead to the fuel trim running rich or lean, triggering this code. These can be things like a defective fuel pump, fuel injectors, or fuel pressure regulator. A clogged fuel filter can also cause this.

Leaks in the air intake or vacuum lines can also cause this issue. This will likely cause the engine to run lean.

In rare instances, a faulty PCM can trigger this issue. This may come with additional fault codes being logged. Also, the PCM can be running on outdated software.

Fixes

Fixes for this issue depend on the system that is causing the fault. This means any other fault codes should be resolved first if possible.

One of the easiest solutions is to replace old engine oil if it is contaminated – then check to see if the P0170 fault code is still present after driving a few test miles.

Any leaks in the air intake or vacuum system need to be fixed. The MAF sensor should be cleaned or replaced. A dirty or clogged air filter should also be cleaned or replaced.

Faulty parts in the fuel system need to be fixed or replaced. Replacing a clogged fuel filter is a good first step.

Seriousness

Fault code P0170 should be considered a moderately serious issue. The inability of the PCM to correct the air-fuel mixture entering the engine can have serious consequences and damage various components down the line

It is recommended to get this issue fixed as soon as possible.