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Q: Error code P0404 on 2001 Chevrolet Tahoe


I have error code P0404, which is EGR system. Symptoms are jerky performance, transmission "hunting" between third and overdrive, and speedometer bouncing all over the place. No other error codes.

Could this just be the EGR valve, or am I potentially looking at the PCM?


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I would suspect you have a faulty EGR valve. The best way to test the valve is with a scan tool. The p0404 code is set when the actual EGR position does not match the commanded position sent to the valve from the pcm. IF you remove the valve and command a fixed position with a scan tool the valve should open to that position and hold. If the valve moves in and out when commanded to a fixed value then the position sensor inside the valve has failed and the valve needs to be replaced.
whats the name of the scan tool i need to find out if i have a bad EGR? Oh yea i have a suzuki verona that has codes 300,0404.0174,0171,2101
Each manufacturer has their on specific scan tool which is designed for their vehicles. The factory specific tools generally perform there functions quite will. There are also aftermarket scan tools available which can work on many different makes and models. The performance of the aftermarket scan tools can vary greatly depending on the quality of the tool.
most likely poor connection or faulty speed sensor ignore code fix trans problem 1st beleive u will find to be main source of code. if engine rpm runs high then low back and forth egr will be forced to open and close errattic faulty speed sensing will deffanatly cause 3/4shift hunt.other causes possible loose valve body ;leaking 3/4 servo rings warn band;do not just tighten any valve body bolts torqed in inch pounds[80/100]
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