6.0 Power Stroke EGR Valve

System Overview

The exhaust gas recirculation system (EGR) is a critical emissions control feature integrated into the 6.0 Power Stroke diesel. Its purpose is to reduce tailpipe emissions of nitrous oxides (NOx), a family of gases found to be harmful. The process achieves lower NOx emissions by recycling a portion of exhaust gases through the intake of the engine and into the combustion chamber. NOx emissions are generated at higher rates when nitrogen is subjected to high temperatures in the presence of oxygen; the EGR system lowers the concentration of available oxygen in the combustion chamber and reduces peak combustion temperature.

The rate of EGR flow into the intake manifold is controlled by the PCM and carried out by an actuator referred to as the EGR valve. On a 6.0 Power Stroke, the EGR valve is commanded between the open and closed states based on a duty cycle between 0 and 45%, with 0% corresponding to the fully closed position and 45% corresponding to a fully open state (maximum exhaust flow into the intake manifold).

The presence of diesel soot in the exhaust stream presents a challenge for the EGR valve because this soot tends to collect on the valve, valve stem, and seats. Prolonged accumulation can impede the movement and function of the valve, which can result in delayed response (slow movement), a limited range of movement, or even cause the valve to become stuck in one position.

EGR Valve Service

Clogged and/or stuck EGR valves are widely common on 6.0 Power Stroke engines. Note that the 6 liter was the first engine used by Ford that employed exhaust gas recirculation technology, and its integration into this engine is generally criticized as the result of the many repeated problems the system can be the subject of. Servicing the EGR valve is actually quite simple and straight-forward; remove and clean the valve, then reinstall it with a new gasket set. The process takes approximately 30 to 45 minutes for the average DIYer with moderate mechanical aptitude. It is not a complex process by any means and requires only basic tools.

I strongly encourage 6.0 Power Stroke owners to service (or have serviced) the EGR valve at least every other oil change or once per year. In my experiences, this is routine enough to avoid excessive soot buildup and circumvent issues with sticking while also maximizing engine efficiency by preventing a fault with the movement of the valve.

Note that modified engines may be more susceptible to EGR valve sticking conditions due to greater amounts of soot in the exhaust. For engines equipped with performance tuners or injector modifications consider servicing the EGR valve at every oil change interval - the same soot that is exiting the tailpipe is also passing through the EGR system.

EGR Valve Cleaning Methods

Once removed from the intake manifold, the EGR valve will need to be cleaned using manual methods. Small brass brushes and a solvent typically make quick work of the task. Acetone, mineral spirits, and brake cleaner all work well at attacking soot deposits. Do not allow any liquids to enter the body of the solenoid where the electronics are housed; concentrate all cleaning towards the mechanical valve apparatus. For stubborn deposits or heavy coking, the valve (again, NOT the housing) can be soaked in solvent over a period of time or between brushing. Wear eye protection and step away from the vehicle while brushing the EGR valve; soot may be flung profusely.

Associated Parts

[1] - Later style EGR valve utilizes a different shaft seal and has a stiffer return spring; they are not interchangeable. EGR valves can be cleaned, reused, and resealed; only replace if unit has failed.
[2] - Includes gasket that seals to intake manifold surface and both o-rings
[3] - Inspect connector wires for chaffing and connector shroud for heat damage; replace only as required
[4] - Replace if stripped or lost; sold in as a set of (2)

EGR Valve Diagnostics

Sticking EGR valves are common because soot tends to build up on the mechanical portion of this component. Heat exposure causes the soot to harden over time, which can restrict or prevent movement. This condition can contribute to poor turbocharger performance and fuel economy, but the exact symptoms depend on the position that the valve is stuck in or how restricted its movement is. EGR valve faults are intended to trigger one or more of the following DTCs:

• P0401 - Insufficient EGR flow detected. DTC is set when EGR valve position is incorrect at that instance, resulting in insufficient flow.
• P0402 - Excessive EGR flow detected. DTC is set when EGR valve position is incorrect at that instance, resulting in excessive flow.
• P0403 - EGR control circuits. DTC is set when a fault in the control circuit is detected (open, short to ground, etc).
• P0404 - Exhaust gas recirculation circuit range/performance. DTC is set detected when the difference between actual and commanded valve position exceeds a specified threshold.
• P0405 - EGR sensor A circuit low. DTC is set when the voltage supply to the EGR valve solenoid is low.
• P0406 - EGR sensor A circuit high. DTC is set when the voltage supply to the EGR valve solenoid is high.
• P0407 - EGR sensor B circuit low. DTC is set when an open circuit or short to ground is detected.
• P0408 - EGR sensor B circuit high. DTC is set when a short to hot (battery +) is detected.
• P1335 - EGR position sensor minimum stop performance. DTC is set when the difference between the commanded and actual valve position exceeds its limits.

In my experience, P0401 and P0402 set with or without a P0404 are the most common DTCs associated with a valve that is overburdened with exhaust soot and cleaning is often an effective solution in restoring its function. Cleaning an EGR valve will not repair an electronic failure.

EGR valve function is quickly and easily tested using an electronic diagnostic tool (scan tool) that is capable of accessing the special tests integrated into the Power Stroke's on-board diagnostic system. Note that not every scan tool has this functionality. The key on, engine running (KOER) self test will test the operation of the EGR valve and return any DTCs. The EGR duty cycle test will allow you to manually command the EGR valve duty cycle between 0 and 45% in 5% increments. It is shown on the Bosch ADS in the figure below.

As you increase the duty cycle, monitor that command and actual states; they should be the same. If the commanded state increases but the actual state does not, the EGR valve is not responding. You'll also note that the engine idle sound will [quite noticeably] change from sharp at 0% to dull at 45%; if there is no audible difference in engine noise, the position of the valve has not changed.

EGR Valve Removal, Cleaning, & Installation

The EGR valve is located between the oil filter housing and intake air horn. It installs through a large hole machined into the intake manifold. It is secured to the intake manifold by two small fasteners that require an 8 mm socket. To begin, remove the electrical connector - the locking mechanism is located at the rear of the connector body.

Next, remove the pair of bolts at the base of the EGR valve mounting flange with an 8 mm socket and an extension (or series of extensions). I use a few wraps of electrical tape to secure my socket to the extension and eliminate the risk of knocking it loose and having to retrieve it from the engine valley. To avoid loosing the small mounting bolts, I grasp them with a long pair of needle-nose pliers once they have been loosened completely.

Once the mounting bolts have been removed, you'll need to pull the valve straight upwards away from the intake manifold to remove it. Doing so requires compressing the pair of o-rings past the sealing surfaces in the intake manifold, thus these can be a little stubborn. I rotate the valve side-to-side while maintaining an upwards force and carefully prying between the valve and intake manifold with a 90 degree angled pry tool.

A special puller (Ford/Rotunda/OTC 303-760) is available for this purpose, but it's rather expensive and I've never been able to justify adding it to my toolbox because I can quickly and easily remove the EGR valve without it. If you do use a prying technique, do not scratch the surface on the intake manifold where the valve seals and note that the ears on the EGR valve mounting flange do bend fairly easily.

Once the valve is removed, vacuum out the opening to remove any loose deposits. I do not recommend brushing or cleaning the opening in the intake manifold. It will dislodge a bunch of material that is difficult or impossible to remove from the intake manifold. Use a shop vac to remove any deposits that were loosened when the valve was removed then leave it be. This is also a good time to wipe off the mounting surface and ensure the new or cleaned valve is ready to be installed.

Looking at the EGR valve, you need to remove the pair of o-rings on the stem of the valve mechanism and the metallic gasket at the base of the housing (refer to figure 8 below). A small pick should be used to retrieve the o-rings, but the blade of a flathead screwdriver might be necessary to peel the gasket from the mounting flange. Take care not to gouge or scratch any of the sealing surfaces.

Once the gasket/seals are removed, begin cleaning the valve mechanism with a small brass brush. Brass is ideal because it is a soft metal and will not scratch up the valve; you can use heavy pressure and aggressive action without leaving any marks of inflicting any damage. After the larger deposits have been broken up I use a small glass jar to soak the valve in a degreasing agent. From figure 9, note that I am not letting the liquid come into contact with the electrical component of the EGR valve, only the valve mechanism itself. It is important that nothing infiltrates the electrical solenoid inside the housing.

As for suitable degreasers, diesel fuel, acetone, mineral spirits, or similar petroleum distillates work quite well in dissolving the soot deposits. From here, cleaning depends on how easily the deposits break apart. I will typically let the valve soak for 10 minutes then remove and scrub it. If stubborn deposits remain, I return it back to the container to be soak again. Repeat this step until the majority of the deposits have been removed. It is also acceptable to leave the valve to soak for a longer period of time.

I find that it's important to clean the seats and faces of both valves. Using a flathead screwdriver, pick, or similar tool, the valve can be propped open so that these surfaces can be cleaned. When doing this, do not force the valve beyond its stop limit. Once I've finished soaking and scrubbing the valve, I clean it off with a few bursts of electrical cleaner (i.e. CRC QD Electronic Cleaner). It works similarly to brake cleaner or carb & choke cleaner, but the solvent is not as harsh and is safe for plastics. Therefore, I don't have to worry about preventing it from getting into the solenoid housing and damaging any of the electrical components.

Once the valve is clean and dry, install a new gasket and o-rings. I install the gasket first because it can be tight squeezing it past the o-rings. After lightly coating both o-rings in clean engine oil or silicon grease (i.e. dielectric), they get installed next. Make sure they seat in their lands properly without twisting or binding by trying to spin them.

Finally, reinstall the EGR valve in the intake manifold. You'll need to apply downward pressure while twisting side-to-side. Once the valve is fully seated, twist it until the ears line up with the threaded holes in the intake manifold and install the bolts. Do not use the mounting bolts to try and seat the EGR valve - it is likely to bend the ears without actually seating the valve, always seat it by hand.

To prevent losing a mounting bolt, I lightly tape them to the end of my socket as shown in the figure below. Once the threads have been started I pull upwards to release the tape. After snugging both mounting bolts, torque them to 120 in-lbs. Reinstall the electrical connector and verify that the valve is working properly, either by driving or using a diagnostic tool. If no DTC is set, the device should be functioning correctly.

Author - T. List
Editor, Diesel Hub