For the following vehicles:
Engine Code: P0491 & P0492 bank 1 and bank 2 secondary air insufficient flow.
Audi S4 2009 - 2012
Audi A5 2010 - 2016
Audi A6 2009 - 2016
Audi A7 2013 - 2016
Audi A8 2011 - 2016
Audi Q5 2009 - 2016
Audi Q7 2011 - 2016
Audi S5 2010 - 2016
Porsche Cayenne Hybrid 2011-2016
Tools needed:
1. Our DIY carbon cleaning kit
2. Pressure Washer recommend 3000 PSI (you can use a smaller one but takes longer)
3. 90* borescope camera (sold on ebay or amazon est $25-50)
4. Basic hand tools.
5. Oil and filter (oil change must be done after repair, prior to starting engine, read instructions to the end before starting this job)
6. Possibly a new water pump and thermostat with gaskets as they will need to be removed for this repair.
Our DIY tool kit comes with the following:
1. Pressure washer adapter hose (hose is laser marked for each port)
2. Straight nozzle fitting
3. 90* nozzle fitting
4. Repair instructions.
5. 2x freeze plugs
6. Engine Crank Socket Tool
Repair Instructions:
1. Move the exhaust sliding bushings (that connect the catalytic converter and muffler) back, then lower the catalytic converter pipes (Figure 4).
2. For Q7, unbolt muffler from catalytic converter. Cover mufflers with a plastic bag to prevent water from entering. Cleaning water will drain out of the catalytic converter pipes during the cleaning process. Figure 4.
3. Lowered catalytic converter pipes
4. Remove all spark plugs and cover the engine harness plugs for the coils (for water protection).
5. Bring the front end of the car into service position (Core support removed, front bumper off) (for Q5, A6, S4, and S5 Cabrio) to make room in the front of the engine. The Q7 has enough room for access to the front of the cylinder heads.
6. For 3.0T only: remove the coolant supply lines (intercooler of supercharger) in the front of the engine (Figure 5).
7. Remove the following components:
• Coolant pipe (Figure 6,1)
• Coolant flange (Figure 6,2)
• Pulley and, if needed, bracket of power steering pump (Figure 6,3)
• Pulley of water pump (Figure 6,4)
• Coolant tube (Figure 6,5)
• Dipstick tube (Figure 6,6)
8. Remove the main port freeze plug by hitting the marked area with a small punch until it turns (Figure 8). Remove with pliers.
9. From here, you will connect the supplied pressure washer hose to your pressure washer with the straight tip pressure washer nozzle tip installed. You need to use this to break through the carbon build up down the center of the port
10. You will know the port is clean when the straight nozzle can go 280mm (11.0”) from the front entrance of the head to the back of the port. (pressure washer hose is marked at 300mm. Please verify its clean with the scope)
11. Now you need to swap out the pressure washer tip to the 90* Fitting. (the fitting just needs to be hand tight, no tools required for installation
PRO TIP: Work cylinder by cylinder, with two people, use your 90* scope to view the exhaust valves opening as you crank the engine over with the provided special tool. When you see the exhaust valves open about 5mm or ⅛” stop and remove the scope. When you are pressure washing and the air port opens up you will here the water spraying onto the back of the exhaust valves.
NOTE: WHEN DONE YOU MUST CRANK THE ENGINE OVER BY HAND TO BLOW OUT THE WATER IN THE CYLINDERS. YOU CAN ALSO USE AIR TO BLOW OUT THE WATER IN THE CYLINDERS. THEN, YOU MUST DRAIN THE OIL AND OIL FILTER VIA OIL DRAIN PLUG. YOU WILL HAVE WATER IN THE OIL. DO NOT RUN THE ENGINE WITH WATER IN THE OIL ENGINE DAMAGE WILL OCCUR.
PRO TIP: with your scope you will see two holes across from another, you need to clean the hole that is closest to the intake manifold. The hole on the exhaust side is just a machining hole for the air port, The hole on the exhaust side does nothing and goes nowhere.
12.a Starting on the drivers side of the car (USA) you will find the 90* air injector ports at the following depth. (see specs above, tool is also marked for driver side and passenger side.
12.b Note in the photo below, the direction the 90* port, on the pressure washer tool needs to point parallel to the head towards the intake manifold.
12.c You will find the markings on the tool. Have one person run the pressure washer trigger and another move the nozzle in and out, past the port. When the port is clean you will hear the water break through the carbon and splash on to the valves.
12.d Now use your 90* scope to verify the port is clean. (see examples below) repeat this step on all 6 cylinders until clean.
Port clogged with small hole:
Port completely clogged (wet):
Port clean after pressure washing:
13. When all 6 ports are clean, spin the engine clockwise by hand quickly a few times. You will see water splash out of the cylinders. Check to make sure the cylinders are dry from water.
14. Install spark plugs, and crank the engine over by hand one more time (2 full rotations) if the engine stops cranking by hand, you still have water in the cylinders. Remove the spark plugs and blow out or evacuate all water in cylinders.
15. Re-install freeze plugs on the front of the cylinder head and re- assemble car. Clear codes and perform 2-3 cold starts to verify the codes do not return.
