How can you tell if the ECU has been chipped in a secondhand car? Obviously dealers are reluctant to admit it, even if they know. Sydney Phillips There are basically three methods of chipping a car. The simplest and arguably least efficient method is to simply connect a device to the EOBD, but this is easily checked by ensuring that there is nothing plugged into the EOBD socket.
The next method is fitting a tuning box somewhere in the engine loom between the engine sensors and the ECU. The tuning box works by altering the data received from the engine before it is relayed to the ECU. Although this may be hidden, it should not be that difficult to find and would very likely be labelled with the makers’ details. Normally unplugging the box and returning the wiring directly to the ECU should set the parameters back to the manufacturers’ specification.
The third method is to re-flash or alter the software in the ECU. This would not be visible and the only way to know if it had been done would be to have the software checked by a main dealer. This could only be returned to its original specification by re-flashing and resetting the software in the ECU. I would imagine that any main dealer would be quite happy to charge you and inform you if the standard software wasn’t installed.