Use your head
Up until recently, buying a used car with an illuminated engine management light was fine for many of us, as it meant we could haggle for a better deal on the asking price. That’s all changed since the MOT revisions from May this year, where there is now a little line in the MOT manual, under
Section 8 Nuisance, that stipulates that an ‘Engine MIL inoperative or indicating a malfunction’ is a MAJOR fault. In other words, an instant MOT failure, regardless of the reason for it.
This has made buying cars with an illuminated malfunction indicator light (MIL) a whole different ball game – if the MOT is looming. The seller may have to drop the value substantially or else the vehicle may well be unsellable until the fault – whatever it may be – is fixed.
Our diagnostics feature, starting on page 6, is based around this change in the MOT. It’s also an acknowledgement that a fault code reader is now an essential component of every motorist’s toolkit. Without one, we either have to ask someone who does to check for fault codes for us, or else make a potentially costly visit to a garage for interrogation of the ECU.
As we all know, a MIL can throw up a number of trouble codes listed under the EOBD format (which came into force from January 1, 2001, on petrol engines and January 1, 2004, on diesel units). Figuring which of these codes directly relates to the problem isn’t so straightforward. This is why our feature also hopes to teach you the importance of not just reading the codes, but correctly interpreting them, too.
This was brought home to me when I became aware of a flashing glow plug lamp on my 2003 Skoda Octavia TDI last month. The car was performing as usual, so it wasn’t immediately apparent what the problem might be.
Luckily, I remembered an incident some years previously, when a MIL led a main dealer to replace the ECU at great expense and that hadn’t resolved the problem. CM’S diagnostic guru at the time, Simon Ashby, was asked to find the cause of the MIL and he found that the rear brake lights were not working.
When I reached my destination, I found a willing person to press the Octavia’s brake pedal and yep, both brake lights and the high-level lamp were non-operational. Later, my Foxwell code reader found a few codes I hadn’t realised were stored in the ECU, along with one tell-tale code for the brake light switch. A genuine part from the Skoda dealer was ordered – a nice £12.10 fix. The glow plugs, of course, were fine.