Problems fixed: Mercedes-Benz, Mini and SEAT

Leading technical supplier Autodata helps you fix three common problems found in passenger cars

The problem

We’re having difficulty diagnosing a fault on a 2016 Mercedes Vito with the 651 engine code. The vehicle came in with reduced engine performance and trouble code P0299 stored in the engine control module fault memory. The customer has also complained of a whistling noise from the engine when accelerating/decelerating. We aren’t sure if the two issues are connected and haven't been able to fix either.

The fix

Similar reports have been posted before and it affects all Vito models with the 651 engine code. The fault is likely to be due to the air intake system blanking plug being loose or fallen out. To resolve the fault, check the air intake system and if the blanking plug is missing, fit a new blanking plug, available from Mercedes-Benz parts department. Tighten the new or existing blanking plug to the correct torque setting of 30Nm. Erase trouble codes and carry out a road test to ensure the fault has been rectified.

The problem

We’re having trouble finding the source of a rattling noise from the panoramic sunroof of a 2015 Mini Clubman when driving over rough roads. We have experienced the rattling noise on road test and have tightened all the nuts and bolts on the panoramic sunroof but we can’t find the source of the rattling noise.

The fix

Other Mini Clubman owners have reported this noise before and it’s due to the panoramic sunroof wind deflector vibrating against the roof panel. If fitted, remove and discard the foam pad. Cut new foam pad, available from Mini parts department into a 40mm x 11mm strip. Fit the new foam pad and carry out a road test to confirm the rattling noise has been eliminated.

The problem

A customer’s 2017 1.0 litre petrol SEAT Arona had an engine oil leak in the transmission area and we replaced the crankshaft rear oil seal. Now the vehicle has come back to the workshop with the same engine oil leak in the transmission area after only a few months. We suspect the crankshaft rear oil seal, but are there any other possible causes before we remove the transmission again?

The fix

We’re aware of an engine oil leak in the area you describe which affects several models in the SEAT range with 1.0/1.4/1.5 petrol engines. The oil leak is caused by an unsatisfactory design of the flywheel retaining bolts due to insufficient quantity of thread sealing compound included at manufacture. Remove transmission assembly, remove flywheel and discard retaining bolts. Thoroughly clean threads on new flywheel retaining bolts and crankshaft. Apply thread sealing compound to new flywheel retaining bolts, available from SEAT parts department. Refit the flywheel using the new retaining bolts. Don’t use an impact wrench to tighten the retaining bolts, ensure flywheel retaining bolts are tightened to the correct torque setting. Refit transmission assembly and carry out a road test to confirm the oil leak has been rectified.

Autodata supplies OEM-sourced technical data and fixes to the automotive aftermarket via its online workshop application.