Tech Tip: Clearing versus diagnosing ECU faults

It’s important to diagnose ECU faults rather than simply clearing them says Bosch

In modern vehicles, electronic control units (ECUs) are everywhere, managing everything from engine performance, comfort and safety systems, airbags and driver assistance features. After an accident or even minor repairs, it is common to find warning lights on the dashboard or stored fault codes. Many repairers take the quick route of just 'clearing' the codes, so the lights disappear.

The problem is that clearing a fault does not repair the cause and it may also permanently remove stored information that could have assisted in resolving the problem. It resets the system temporarily in the case of an intermittent fault. The issue can return as soon as the vehicle is driven again. That leads to comebacks, wasted workshop time, unhappy customers, and possible safety risks if the fault involves critical systems.

Utilising pre- and post-scans of all vehicle systems and saving the information can save time and arguments after the car has been returned to the customer. Where supported by the manufacturer, freeze frame data (a snapshot of the operating environment of the vehicle when the fault was logged) is invaluable in determining pre-existing faults versus accident-related faults. This assists with accurate quoting and reduces arguments with customers and insurers.

Diagnosing, on the other hand, means finding out why the fault code is there in the first place. It could be a disconnected sensor, a wiring fault, or a damaged radar mounting bracket causing an alignment issue hiding behind replacement panel. Proper diagnosis gives you the chance to repair the underlying issue, recalibrate the system if needed, and return the vehicle in full working order.

The lesson is simple. Clearing codes makes warning lights disappear, but diagnosing a fault and proper record keeping of faults rectifies the problems. Getting this right saves you money, protects your reputation, and most importantly, keeps the vehicle safe for the customer.

Bosch ESI[tronic] Diagnostic Solution

For workshops looking for the right tools to move from "code clearing" to real "fault fixing", Bosch offers the ESI[tronic] ECU Diagnostic Software. It provides guided troubleshooting, wiring diagrams, test values, and repair instructions across a wide range of makes and models.

The professional, timestamped reports generated by the Bosch Diagnostic tool clearly display pre- and post-scan data, effectively eliminating disputes regarding pre-existing faults. Furthermore, these reports provide crucial documentation to substantiate any additional repair costs.

Important notes for workshop use:

• ESI[tronic] requires a compatible Bosch VCI module, either KTS 560 or KTS 590.
• Using ESI[tronic] also requires selecting and purchasing the correct software subscription that best suits your needs.

Bosch ESI[tronic] is available in Australia from:

• CoolDrive
• HSY Autoparts
• Mount Auto Equip Services

Tech Tip Takeaway: Don’t just clear fault codes, diagnose the cause and fix it right the first time using the correct tools and software.