01 Park Ave surging

[pcabn]

Car is surging at 35 to 50 clears up after that......engine light is on.... codes P0141 HO2S Heater Performance Bank 1 sensor 2, P1404 EGR clsed position P0420 low efficiency catalyst. Car is not surging at idle or any other speed.

I am looking for the right way to trouble shoot this. I don't know if I have three issues or perhaps one issue is causing the others.

The engine is the 3800 non supercharged. 193,000 miles. Thanks

[maxwedge]

Well your o2 sensor or wiring is bad, an egr problem can cause surging at low speeds, cat unless blocked is not affecting hour issue.

[pcabn]

O2 sensor will be replaced tomorrow Not sure if the egr valve is bad or there is some carbon build up. Will replace the Oxygen sensor tomorrow and try to determine what's up with the egr valve. Thanks.

[Tech II]

A partially blocked cat can build up back pressure in the exhaust, which can possibly unseat the EGR, causing a code for the pintle position, and also a surge....

More often than not the heater circuit for the O2 sensors, can short out due to a rub through condition in the harness to the O2 sensor.....

[pcabn]

O2 was definitely bad codes cleared up for two days.Egr code came back yesterday but cleared or pass test when I drove it again. When testing the egr the solenoid is operating so not sure at this point what is happening. Can't work on it until next week sometime The catalyst code hasn't come back. Thanks for the replies I sure appreciate it.

[pcabn]

Oh yea surging has cleared up....at least for now

[sktan]

Have you checked the EGR system? maybe you need to clean the EGR valve and Cooler.

[pcabn]

Haven't had a chance the code is still clear