The dreaded P0400 code is a common problem of the Suzuki X-90, Sidekick, and the Tracker. Many owners may invest a good deal of money replacing parts in an effort to correct the problem, but find that they still have the code. When I purchased my X-90, I inherited repair receipts from the previous owner indicating that they had replaced the EGR valve and the O2 sensor. When my newly-purchased X-90 failed emissions testing, I was working against a deadline (14 days in WA state) to bring it into compliance (or spend $150 attempting to bring it into compliance to qualify for a waiver). The EGR solenoid was replaced by a WA state authorized emissions specialist; it didn't solve the problem, but the repair bill exceeded $150 allowing me to transfer ownership of the vehicle into my name. Still, I wanted to correct the problem, emissions waiver notwithstanding. A reasonable amount of internet searching provided my answer...
The solution is surprisingly simple: clean the EGR pathway.
Step 1. Locating the point of obstruction
In the photo below, note the red dotted line on the top of the intake manifold. Directly below that red dotted line is a partition with an aperture approximately one half inch in diameter. This aperture is prone to clogging with carbon. It must be clear to allow for an unrestricted flow of the EGR. Otherwise the ECU will generate a P0400 code.
|
|
Step 2. Remove and clean the EGR tube
Mouse over the photo below to see the EGR tube outlined. This tube must be removed and cleaned. You will likely need to remove the battery first to attain reasonable access to that area. As for cleaning, carb cleaner and a brush will suffice; ensure that the tube is unobstructed. My buddy Adam had the smart idea to put the hose of his air compressor tool to one end of the tube and blast some air through.
|
|
Step 3. Detach the intake pipe
Mouse over the photo below to see the intake pipe outlined. This pipe must be detached at both ends and then moved aside to ensure access to the throttle plate. You'll likely need to detach some, but not all, of the connecting tubes along the side of the intake pipe. |
|
Step 4. Open the throttle plate
Depress the accelerator to open the throttle plate (butterfly); while the throttle plate is open, have an assistant insert a screwdriver into the throttle mechanism to prop it open. |
|
Step 5. Examine the EGR aperture and clear if necessary
Using a flashlight, look into the intake manifold past the open throttle plate and locate a 1/2" hole on internal partition. This hole should be unobstructed. On my X-90 it was almost entirely blocked. In fact, we inserted a pen light up into the EGR port of the opposite side of the intake manifold, and when we looked in past the throttle plate the amount of light we could see coming through was just a tiny hole (about the size of the tip of a ballpoint pen).
Insert a wire brush into the port to which the EGR tube connects (see red arrow in photo below) and move the brush to and fro to loosen the carbon buildup. The EGR tube is not present in the photo below, as it was removed in Step 2.
|
|
| Insert a long screwdriver into the intake, past the throttle plate (see red arrow in photo below), and press against the EGR aperture to break through the obstructing carbon buildup. It is advisable to have an assistant hold the suction hose of a shop vacuum against the EGR port (on the opposite side of the intake) to extract the debris. |
|
| Finally, ensure that the aperture is unobstructed by conducting a visual inspection. In the photo below, we inserted a pen light into the intake manifold to aid in the examination. Mouse over the photo below to see the unobstructed aperture outlined. |
|
| When the battery is reconnected you will likely find that all the DTC data has been lost and the SES (Service Engine Soon) light will be off. Assuming that all other components of your EGR system are fully functional, the P0400 code should not return. |
