The camshaft adjuster leaks oil internally and this goes into the wiring loom (harness). The oil travels along the loom and usually ends up at the lamda sensor (O2) on the exhaust. If you're unlucky, it goes into the engine ECU...more money!

This can be avoided by fitting an in-line loom mod bit, which is about 6" long and is designed to absorb oil and not let it pass through to the loom... The problem is only on later 111 engines - very last of the 202 c class, early 203 c class & 208 clks...Part number for the mod is 2711502733 £14.36+vat.

I would recommend anyone who has an early 203 4 cylinder with engine number starting 111 buys this part. It is an easy DIY fit. Remove front engine cover trim & plug new loom between cam adjuster & old loom.

This may save you £1000+"