How Electronic Power Steering DTCs Work

When it comes to diagnosing electronic power steering issues, your diagnostic scan tool provides the very first step to repair. Because electronic sensor and communication problems cannot generally be identified by sight or sound, your scan tool will point you toward what's wrong with the system. However, there's a limit to just how much information your scan tool can provide and in what format. Scan tools, in general, can't tell you exactly what's wrong with the vehicle, but they all provide diagnostic trouble codes (DTCs) for your team to interpret and test. In this post, we'll discuss how electronic power steering DTCs work, how to read them, and how they can help your techs prep their repair plan for success.

What Are DTCs?

DTCs are the coded messages your scan tool uses to identify the issues the EPS system (as well as other onboard systems in a vehicle) is experiencing. When you connect your scan tool and run diagnostics, the DTC(s) that return can point you toward the area or system that needs your technician's attention, and sometimes it can also provide some information about what the problem may be. DTCs tend to be fairly standard across all scan tools, though you may run into an unfamiliar or brand-specific DTC from time to time.

OBDII DTCs consist of one letter and four digits that correspond to a certain type of fault in the system. The letter in the code corresponds to the system where the problem is located:

• B: Body
• C: Chassis
• P: Powertrain
• U: Network & Vehicle Integration

For EPS, the majority of codes you can expect to encounter are C, which deal with functions like brakes, steering, and suspension, and U, which are related to computers in the system. However, many DTCs can help you start to diagnose the issue but cannot completely identify which component in the system is the cause of the issue. At that point, it becomes the job of your technicians to either use their previous experience with this code or dive deeper into the system in order to determine which parts need repaired or replaced.

Using DTCs to Diagnose and Service EPS

Once the DTC has been retrieved by the scan tool, your technicians can begin to test and investigate the issue that's been identified. In many cases, the jump between the code and the actual problem is one of the most challenging parts of EPS service. For issues at the component level, the process tends to consist of testing and replacing the pieces in the system until the problem is resolved. Intermittent diagnostic scanning will be necessary in order to ensure the correct repair has been made during any EPS service. For communication issues, this is the point where a different level of service may be necessary. The need for an investment in your business in regard to EPS is most apparent when it comes to troubleshooting electronic components. This level of training can be hard to come by from major manufacturers, leading to one of the largest issues with EPS service at this time. In order to service electronics, your shop may need to make a big transition in terms of resources and personnel.

In order to aid your technicians in identifying EPS failures, lists of DTCs are widely available online, in addition to in a list that should come with your scan tool. When in doubt, it's always helpful to type the DTC into a search engine for more information, and your team may even find service or troubleshooting tips from other EPS techs and programmers online as well. In the rare case that the scan tool returns with no code despite an obvious issue with the vehicle, more extensive research and expertise may be required. In the vast majority of situations, however, the DTC will give you the best idea of where to start the repair at the system level. It's then in your tech's hands to take care of the issue at the component level using the training and information they have at hand.