The engine of the Renault used in our example is : petrol engine 1.6 16V 95 hp.
We diagnosed the vehicle, a 2005 Renault Kangoo using an ELM327 and our EOBD-Facile software. This Kangoo was losing power, the MIL indicator on the dashboard was lit. Reading of the fault codes confirmed a single fault: P0303. The vehicle electronics detected an ignition problem on cylinder 3. To identify it, check a technical automobile review. Otherwise, cylinder no. 1 is usually next to the flywheel (in our case no. 1 is on the right in the photo), then count up to 3 from the left.
Initially, start with usual basic verifications. Have the ignition plugs been replaced regularly? Is there a connection problem or a breakage? Is the electrical harness cut or worn? In our case, the vehicle had been services and no apparent problem was detected.
Looking more closely (fig 3-1), we can see that one of the ignition plugs (cylinder no. 2) has green plastic. This is not the original part and has already been replaced. Some petrol engines at Renault have experienced weakness in the ignition plugs (a quick search on the internet confirms this)
Removing the plug (fig 3-2) to test it will allow us to confirm this hypothesis. After removing and replacing the coil, the car seems no longer to suffer from a loss of power. The fault code can now be cleared before doing a road test and confirming using mode 7 available in EOBD-Facile that the fault has really disappeared.