The video below shows a diagnostic test being done on a Peugeot 308 from 2008 where the information section of the dashboard is displaying the message 'depollution system faulty'. For the diagnosis we used an Autel MD802 DS however the cheaper Autel MD704 will do exactly the same job here. The code reader when diagnosing the engine gave us the error code 1340 which is a P code, P1340 which means there is a misfire in cylinder 4.

This code is sometimes misleading and could mean that the timing is off and the timing belt needs to be changed, or a camshaft sensor needs to be replaced. Take a look at the video as you might have the same problem on your Peugeot 308.

Below the video you will find out what the exact fault was in this circumstance, and how it was corrected.

We replaced coil number 4 and put in a new set of spark plugs and the engine began to run fine again. We used the MD704 to clear the fault code and cleared the engine/MIL/EML from the dashboard.

This procedure is exactly the same for fault codes P1337, P1338 & P1339 which relate to cylinders 1, 2, 3 & 4.

The chances are if one coil has gone, the others will not be too far behind, so while you have the engine cover off you many aswell replace all coils at the same time. In this case there are only 4 coils, 1 per cylinder.