U0106 Fault Code

Long Description

Fault code U0106 is a communication-related code that is logged when the onboard computer detects a loss of communication between the onboard control modules and the glow plug control module.

The glow plug control module is responsible for providing the information from the powertrain control module (PCM) to the glow plug relay, which in turn controls the various glow plugs in each cylinder.

Glow plugs are used in diesel engines to provide heat to the cylinders during starting operations. This is done to allow the air-fuel mixture to ignite with pressure alone. This also means that only diesel engines have a glow plug control module.

Some of the most common manufacturers to suffer from this code include Chevrolet, Dodge, Ford, and Jeep. Again, only their diesel offerings will be able to have this code logged.

Other Signs of This Problem

Issues with the glow plug control module will typically come with a number of noticeable symptoms. These will be particularly relevant during a cold start, and made even worse in cold environments.

The most obvious sign will be that the Check Engine light is illuminated on the dashboard.

In some cases, there will be an even more noticeable issue – the vehicle will crank but not start at all.

Be sure to look out for additional codes that relate to the glow plugs. These will typically include P0380, P0381, P0670. It is very likely that P0670 will be logged as this code indicates a circuit issue for the module.

What Could Be The Problem?

Because this code is related to the communication of the various onboard systems, the cause will likely be electrical in nature.

One of the most likely causes is an electrical issue between the PCM and the glow plug control module. The controller area network (CAN) bus may be suffering from an open or short circuit in one of its connections. This can include a short to power or short to ground in either circuit.

It is also possible that the glow plug control module is faulty.

In addition to this, the PCM could be defective, but this is rather rare. It will also likely result in multiple various codes being logged.

Fixes

Fixing this fault code, like many other communication codes, will require electrical know-how as the cause is almost certainly electrical in nature.

It is important to check that the glow plug control module is not faulty. If it is determined that it is, it should be replaced. Fault code P0670 is a clear indication that the problem lies within the module’s circuit.

The circuits need to be checked for electrical issues. Damaged wires and loose connections need to be repaired accordingly. This must be done for both the positive and negative CAN bus wires.

Any open or shorts to ground or power need to be fixed.

If the PCM is determined to be at fault, it needs to be replaced. It is also possible that the PCM needs a software update.

Seriousness

Fault code U0106 is a serious issue. A glow plug control module that is not functioning properly can cause the vehicle to not start or have a very difficult time doing so.

It is highly recommended to have this fault code fixed immediately.