Air leaks in the intake system, checking (B5234T3; B5244T3; 2001): Check

Adjust the regulator to obtain a maximum pressure of 0.3 bar  (0.15 psi). There may be a gentle hissing sound from the oil filler opening. This is due to the opening of an intake valve and the leakage of cylinder pressure past the piston rings.

Check components and connections. See: Checking components .

If a leak is suspected, spray a soap solution onto the area. Check for air leakage from the canister purge (CP) valve. No leakage is permissible.