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O2 Sensor just replaced, no runs rough..?

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5 replies to this topic

#1 gogi (converted)

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Posted September 1, 2007 at 07:21 am


My service enginge light had been coming on for about a year and when I brought my mini in to get inspected they told me I need a new O2 sensor. Now the service engine light is off, but the engine seems to be running a bit rough. Do I need to get a tune up after replacing the O2 sensor or did something else happen?

Dodge Grand Caravan 97 3.3/V6, 94K miles

Thanks gogi


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Posted September 1, 2007 at 08:53 am

There are two sensors, an upstream in the exhaust manifold and a downstream near the convertor, which did you replace?

#3 t2erns

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Posted September 1, 2007 at 10:09 am

what was the trouble code (cause of ses light on)? what made them identify it as a defective O2 sensor? trouble codes does not specifically identify a failed part but rather a circuit failure so shotgunning the part is not the proper approach.you may have other issues regarding the rough running of the engine. since you mentioned that the service light was coming on for a long time i can guess that you have a failing catalytic converter that's plugging the exhaust, the inspection test may have a gotten a trouble code for the oxgen sensor that's why they told you to replaced it (catalytic converter efficiency is determined by comparing the upstream and downstream O2 sensor activities) there are also other things that may cause a rough running engine so i guess you need the aid of a scanner. BTW upstream O2 sensor is for A/F control while the downstream O2 sensor is primarily for the catalytic converter efficiency monitor.

#4 A. Murphy

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Posted September 1, 2007 at 04:27 pm


Dodge Grand Caravan 97 3.3/V6, 94K miles

Thanks gogi

I'll assume they changed the upstream one given it is the one most likely to fail. OEM of some aftermarket brand?

if not already done, 97 is good enough to replace the plugs and wires. Maybe give the throttle body a clean and change the air filter if dirty, but that's about it. nothing else in there you can "tune".

Might be worthwhile put a OBD tool on it and monitor the activity of the O2 sensors.

Check your fuel pressure, jic it is low, this woudl cause poor performance if too low.

#5 Beans

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Posted September 1, 2007 at 08:01 pm

What if THEY put the wrong sensor in?

#6 gogi (converted)

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Posted September 2, 2007 at 09:58 am

I am not sure which sensor they replaced, I will try to find out. Before I had the sensor it ran great. The only problem was the serpentine belt which was replaced along with the tensioner and another pulley. It did not start making the noise until after the o2 sensor was replaced. I am not a trained mechanic, but it sounds like the noise is coming from the rocker arms or valves. It drives fine except for the new noise. I always check for leaks after having parked it for awhile at the mall and have seen nothing. Oh, my air conditioner is not blowing cold air now. The fan dial has four settings and the first two don't even start the fan. I feel like every $300 I put into this springs 2 new problems. ugh..!!!

Just frustrated. This thing was running great until the belt problem started.

Thanks for all the help.



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