What Inspired the OBD X BOX?

Since around the mid 1980’s I’d developed a passion for diagnosing and repairing early engine management system faults on petrol fuel injected cars. The main tools I used back then were a Crypton 440 Cruise Mate with 4 gas analyzer and various handheld multi-meters and real time live oscilloscopes.

Around about 1988 I bought my first ECU Scan Tool; this was the brand-new Crypton Check Mate made in Bridgewater, Somerset by Crypton Technologies. Other diagnostic tool manufacturers soon brought out similar Scan Tools, all these connected to the vehicles ECU using connectors specific to various vehicle manufacturers around at that time.

A few years later the industry was standardized with all vehicles using the same type 16 pin OBD diagnostic port and EML (Engine Management Light). Not long after this, Common Rail diesel (CRD) engines started using the same OBD technology as they were also installed with complex engine management systems very similar to their petrol variants.

All this new technology should have helped our motor vehicle Technicians, but in some cases, it made our task of diagnosing and repairing vehicles more difficult. Firstly, the general public now believed we had a magic box that just plugged into the OBD port and automatically told us exactly what was wrong with their vehicle. Secondly, their vehicle handbook told them in most cases that if the EML came on they must not drive the vehicle, this has caused the motor trade all sorts of problems. Roadside Recovery Breakdown companies such as the AA, RAC and Green flag are inundated with customers refusing to drive their vehicles because they have the EML on.

From many years’ experiences in this trade, I can honestly say that in most cases it is still safe to continue driving a vehicle with the EML on. Unfortunately, most customers don’t possess our understanding of vehicles, and some wouldn’t want to make the decision to drive with the EML on.

So, for many, many years I’d been diagnosing engine running faults without the help or hindrance of an EML coming on or the engine going into Limp Mode, so now what? A lot of my self-taught methods of repairing and diagnosing faults involves different types of emulation to prove if an engine can be made to run correctly, even before repairs are carried out.

So, I thought to myself, how can I use Limp Mode to test the running capabilities of an engine and how can I use the Engine Management Light to my advantage?


When an engine is stuck in Limp Mode a technician would normally have to diagnose and repair any known faults before proving the engines drivability. I soon worked out that by deleting EML codes as fast as 10 times per second would enable most vehicles to be driven out of Limp Mode as if the fault does not exist. Using this method would confirm individually if the engine’s, exhaust system, fuel supply, turbo, EGR or DPF were working correctly by selectively targeting and deleting chosen fault codes.

Although not quite the same as emulating voltage, vacuum or pressure, I’d now found a new method of diagnosing and influencing the vehicles Management System using the OBD.

The EML is your friend.

You may not think so at times, but the EML is there to tell you as a customer and as a vehicle Technician that all is not well, used correctly it can assist you in diagnosing any EMS faults.

A Garages worst scenario is when engine repairs have been carried out on a vehicle and charged for, and then the vehicle is returned soon after with its EML back on.

Similarly, a customer keeps coming back to tell you his EML is staying on but then randomly going off but then coming back on again, whilst not able to give you any valuable information.

Some customers can be quite reasonable and understanding whilst others are not, they will become a garage owners’ worst nightmare by refusing to drive the vehicle if the EML is on.

I soon realized what was needed was a means not only to target and to delete selected fault codes but also to monitor how frequently they occurred. Furthermore, if I could use the Customer to assist me as to when, and under what conditions any faults were most pronounced, then this would help to diagnose any faults much sooner.

An optional Piezo beeper was added to the OBD X BOX so that Customers could now monitor precisely and report back to the garage under exactly what engine speed, temperature and loads etc. they heard the beeper sound. Armed with this previously unavailable information the Garage would now have a much greater chance of diagnosing the fault.

As Fuel Injection Specialists ourselves we have been using the OBD X BOX during its development for over two years now with fantastic customer feedback. Not only have we experienced amazing and time saving results, but we have significantly increased workshop profitability too.

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