Valve covers on A14 NET NEL engines become damaged over time. To diagnose a cover failure, leave the engine at idle speed, obtain a thick foam, e.g. to check the tightness of the LPG installation, and proceed as in the video:


  • Uneven idle speedIncreased oil consumption, heavy smoke, too blue, especially when adding gas
  • Problem with unscrewing the oil filler cap when the engine is running (the cap is strongly sucked to the cover)
  • Problem with removing the dipstick with the engine running (the dipstick is strongly sucked inside)
  • Suction of "left" air exhaust valve vent hole. Error P0171 (lean mixture)


In most cases, diagnosing a damaged cover is quite simple. If there is a strong suction of the oil filler cap or the left air is sucked in through the vent hole of the pneumothorax valve, we are 100% certain that the cover is damaged. Sometimes, however, it happens that the cover does not show any signs of wear, but is still damaged and causes increased oil consumption (up to several liters per 100 km. This leads to heavy smoking. Below we present videos with examples of covers: 1.6 XEP, 1.4 Turbo 120-140 HP, and 1.6 SIDI 170 HP, in which we show how to check whether the diaphragm valve is damaged.

Attention ! Before replacing the cover with another one, be sure to read it!!

There are two causes of damage to the valve cover diaphragm:

The membrane works in oil vapors, so after about 5 years of operation, it ages and cracks. In the 1.4 Turbo A14 NET, A14NEL 140 HP and 120 HP engines, there is a small non-return valve in the intake manifold, which wears out over time and flies out of its seat. If this happens, overpressure is created in the crankcase, which very quickly damages the diaphragm in the valve cover and causes oil leaks, among others, from the valve cover and throttle. Driving with a damaged plug drastically shortens the life of the valve cover diaphragm. Therefore, before regeneration, check whether the valve in the manifold is operational.

The description of checking the valve can be found here:

When assembling the cover, it is recommended to use a gasket:
VICTOR REINZ no.: 71-42349-00

ELRING no.: ELR 773.410

This is quite important for the proper operation of the cover.