2001 Chevy Suburban dies - Code 404


Old 12-15-10, 11:33 AM
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2001 Chevy Suburban dies - Code 404

My wife recently was out in our 2001 suburban when it died twice on here in a 3 mile stretch. She took it to a local "mechanic" who said his scanner is showing code 404 wihch equates to an ERG issue. He said though, changing it won't fix the issue and it is probably the fuel pump. She's had issues with rough idling before in cold weather but this issue is new. Has anyone had such an issue or experience in fixing it? It is a 4x4 1500 with 106K miles on it. just recently had the fuel filter changed, the idle air sensor replaced and intake manifold gaskets replaced and that did not fix a thing.
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Old 12-15-10, 02:35 PM
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I would go for the fuel pump.
Next time it quits try hitting the bottom of the tank with a 2 by 4 to see if if goes again. They are bad for that sorry to say.
Old 12-15-10, 03:17 PM
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OBD-II Trouble Code Technical Description

Exhaust Gas Recirculation Circuit Range/Performance
What does that mean?

The EGR (Exhaust Gas Recirculation) system's purpose is to redirect exhaust gas back into the cylinders. Since exhaust gas is inert, it displaces oxygen and fuel, thereby lowering cylinder temps, which, in turn, lowers oxides of nitrogen emissions. For that reason it needs to be carefully metered into the cylinders (via the EGR valve) so as not to adversely affect the engine's performance. (Too much EGR and the engine won't idle).

If you have a P0404, then the EGR valve is likely an electrically controlled EGR valve instead of a vacuum controlled EGR valve. Also, the valve will usually have a feedback system built into it that informs the PCM (Powertrain Control Module) what position the valve is in; open, closed, or somewhere in between. The PCM needs to know this to determine whether or not the valve is operating as needed. If the PCM determines that the valve should be operating, but the feedback circuit shows that the valve is not open, this code will set. Or if the PCM determines the valve should be closed but the feedback signal indicates that the valve is open, this code will set.

There may be no symptoms of a P0404 DTC other than the MIL (malfunction indicator lamp) or check engine light. However, Exhaust Gas Recirculation systems are inherently problematic due to carbon buildup in the intake manifold, etc. This normal buildup can lodge in an EGR valve, holding it open when it should be closed. If this is the case, the engine may idle rough, or not at all. If the valve has failed and is NOT opening, then symptoms would be higher combustion temps and as a result, higher Nox emissions. But the latter symptoms aren't going to be noticeable to a driver.

Usually this code points to either carbon buildup or a bad EGR valve. However that doesn't rule out the following:

* Open or short in the 5 Volt reference circuit
* Open or short in the ground circuit
* Open or short in the PCM controlled voltage circuit
* Bad PCM (less likely)

Possible Solutions

1. Using a scan tool command the EGR valve to open while watching the actual EGR position (it will probably be labeled "desired EGR" or something similar). The actual EGR position should be very close to the "desired" EGR position. If it is, then the problem is likely intermittent. It may have been a lodged piece of carbon that has since dislodged, or it could be a bad EGR valve winding that intermittently opens or shorts as the valve temperature changes.
2. If the EGR "desired" position is not close to the "actual" position, then unplug the EGR sensor. Check for a good 5 Volt reference voltage to the connector. If it doesn't show a reference voltage, repair an open or short in the 5 Volt reference circuit.
3. If there is a 5 volt reference voltage, activate the EGR with the scanner, monitor the EGR ground circuit with a DVOM (Digital Volt/Ohm meter). It should indicate a good ground. If it doesn't then repair the ground circuit.
4. If there is a good ground, then check the control circuit. It should indicate voltage that varies according to the percentage that the EGR is open. As it's open more, the voltage should increase accordingly. If it does, then replace the EGR valve.
5. If the voltage doesn't increase incrementally, then repair open or short in EGR control circuit.

and yes, it can choke the engine. keep it simple - remove EGR, it is not that hard, and clean it well with carb cleaner. careful with gasket, those are usually metal or metalized, and tare easily.

your burban is basically my silverado, and on mine, getting to fuel pump is a *****. maybe they made service lid for it in the floor on yours. no, they did not. you will have to drop tank down.
also, you have electronically controlled EGR, so i am not even sure you can clean it. i cleaned, succesfully, only vacuum controlled ones. you need to check voltage on it as above.

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