This article gives detailed instructions on replacing the air pump control valves in a BMW vehicle with the 8 cylinder N62 engine. Even though we used a 2005 645ci to perform this repair, this article can be applied to any vehicle with the BMW N62 8 cylinder engine including 5,6,7 and X5 models with minor modifications to the repair steps.
The BMW N62 air pump control valves are a known source of failure in the V8’s emissions system.
One of the more overlooked (and misunderstood) systems in our BMW vehicles is that of emissions control. Emissions control is the process of reducing the hazardous air pollutants that are emitted from a vehicle as a byproduct of fuel combustion. These hazardous pollutants include hydrocarbons, carbon monoxide (CO) and other volatile compounds that are considered dangerous to human health and the environment.
One of the critical components in reducing hydrocarbon and CO emissions in our BMWs is the secondary air injection system – a method of injecting outside air into the exhaust manifold during a cold engine start. Injecting fresh outside air into cold engine exhaust gases helps the catalytic converter reach its operating temperature faster, reducing the amount of unburned hydrocarbons emitted from the vehicle. The secondary air injection system relies on an electric air pump which directs outside air into the exhaust manifold through a network of pipes, and two non return valves. These non return valves, also know as air pump control valves, are basically check valves located on each of the V8’s two exhaust manifolds. They allow the fresh outside air from the secondary pump to flow into the exhaust manifolds without allowing dangerous gases to flow back in the opposite direction into the pump. Without the air pump control valves, dangerous gases would flow back into the engine when the secondary air pump shuts off.
Unfortunately age and general wear and tear take their toll on the BMW N62 air pump control valves, causing them to malfunction. Dirt, debris, and mechanical malfunction can cause the valves to stick open or closed triggering the dreaded “service engine” light in the instrument cluster as well as displaying emission system warning messages on the iDrive display. BMW N62 air pump control valve failure will also produce error codes including P0491 and P0492.
Replacing the air pump control valves on the N62 eight cylinder engine is unfortunately not a simple process. The valves and the pipes that connect them to the secondary air pump are located underneath the intake manifold. The intake manifold must be removed to replace the air pump control valves in the N62 engine…it is impossible to access them any other way.
When performing an air pump control valve replacement on your BMW N62 engine, we strongly recommend replacing the pressure hose assembly that supplies the air from the secondary pump. The pressure hose assembly is made of plastic and is notorious for becoming brittle and cracking with age. We cannot stress enough spending the few extra dollars and replacing this pipe while you have the engine disassembled. Also it is very important
1. Air pump control valve (required) – The BMW N62 air pump control valve is a simple check valve that keeps exhaust gases from flowing backwards into the engine. Although simple in design, it is a precision part that should only be replaced with one of OEM quality. Always replace both valves…even if you are only getting an error code on one of them. We give you a couple of great choices based on your brand preference and budget.
2. Intake manifold gaskets (optional) – Since the intake manifold will need to be removed for this repair, it is good practice to replace the gaskets before reassembly. New intake manifold gaskets are cheap insurance against future vacuum leaks in your engine.
In order to gain access to the BMW N62 air pump control valves, the intake manifold must be removed. You cannot remove the air control valves with the intake manifold in the vehicle. This is because the pressure hose assembly that connects the air pump to the valves is underneath the intake manifold…it is not possible to reach its connections otherwise.
- To remove the intake manifold from your N62 engine, please see our article BMW N62 Intake Manifold Gasket Replacement – V8 5,6,7 and X5 Series before proceeding to the next section.
Once the intake manifold is removed, replacing the control valves is a simple procedure. They are simply attached to the top of each exhaust manifold with two bolts. There is a very good probability that you will break the plastic pressure hose assembly while removing the valves. DO NOT get discouraged…this is a very normal occurrence. The pressure hose assembly becomes very brittle with age and in older vehicles it is nearly impossible to remove without it falling apart in your hands. If you break yours, please see our parts block above to reorder or click here to purchase a replacement.
- Locate the two air pump control valves. They are located at the rear of the engine.
- Starting with the right control valve, squeeze the pressure hose assembly fitting and pull it free from the valve. Repeat on the left valve.
- The air pump control valves are anchored to the exhaust manifold with two bolts. Use a 10mm socket wrench with a long extension to reach them.
- Grasp the valve and remove it from the engine. Make sure to remove the old sealing gasket with it.
- When reinstalling the new air valves, make sure to use a fresh sealing gasket. Their should be new ones included with your new valves.
Reassembling the vehicle is very straightforward with no special procedures. We have provided a handy checklist below for your convenience to help with reassembly.
BMW N62 Air Pump Control Valve Reassembly Checklist
- Install the new control valves. make sure the new sealing gaskets are properly aligned with the mounting holes. We suggest using a little spray adhesive to keep the gaskets from sliding out of position.
- Install the mounting bolts and torque them to 10.5 Nm (7.75 ft-lb).
- Reinstall the pressure hose assembly to the control vales. make sure they snap securely in place.
- Reinstall the intake manifold following the instructions at BMW N62 Intake Manifold Gasket Replacement – V8 5,6,7 and X5 Series.