Test EVAP System
If vehicle is not LDP-equipped:
- Plug or clamp EVAP canister outlet and proceed to step "Continued for all vehicles" (below).
If vehicle is LDP-equipped:
- Plug or clamp LDP inlet (filter side) using Special Tool No. 3094 or equivalent.
- Attach fuel cap adapter to filler neck (arrow) and test hose to adapter.
- Turn control valve from "Hold" to "Test".
- Allow fuel system to pressurize.
NOTE:
Fuel system pressurization depends on volume of fuel system and amount of fuel in tank.
If fuel system pressurization does not stabilize:
- Verify all fuel system outlets have been sealed before continuing.
CAUTION:
Clamp only soft rubber lines when isolating a leak. To avoid risk of damage, never clamp hard plastic lines!
NOTE:
Any flow shown on flow meter indicates a leak. Flow before flow meter flag set at vehicle leak standard may indicate a sporadic DTC.
If flow meter on tester registers flow near or above preset pressure:
- Clamp off hose (arrow) leading from EVAP purge regulator valve -N80- to intake manifold (pictured: AHA engine in A6).
If flow stops:
- Replace EVAP purge regulator valve -N80- and repeat test before continuing.
If meter indicates no flow after test:
- Perform a quality check and return vehicle to customer.
If flow continues, proceed as follows:
Method 1: Locate leak with smoke generator
- Connect leads from smoke generator to vehicle battery.
- Use smoke generator trigger to charge fuel system with smoke.
- Inspect complete EVAP system for escaping smoke.
Method 2: Locate leak with ultrasonic tester
General search: tester only
Localized search: tester with extension (on left in illustration)
If leak cannot be located:
- Disconnect and plug or clamp shut EVAP lines to isolate fuel tank, using Special Tool No. 3094 or equivalent, before continuing.
CAUTION:
Clamp only soft rubber lines when isolating a leak. To avoid risk of damage, never clamp hard plastic lines!
If flow stops:
- Reconnect EVAP lines to search area that was isolated
If leak or source of fuel odor cannot be found:
- Contact Audi Dealer Technician Helpline.
CAUTION:
Under no circumstances should the vehicle be returned to the customer without proper diagnosis and repair.
When leak has been located:
- Repair leak and repeat EVAP system test.
- Perform quality check and return vehicle to customer.
NOTE:
- Because leak may be at top of fuel tank, it may not be possible to locate through fuel pump/sending unit access plate.
- Fuel tank may need to be lowered to locate the leak.