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Getting ready for California smog check I removed the headers and cat and put back on the stock exhaust manifold and California Cat. She ran great...and then she didin't. Wouldn't make power.
Jiggled the cable from the O2 sensor at both ends, and she ran great again. And then not. Obviously an intermittent short or open.
Working with it today it just wouldn't get better. When I pull the big square connector apart...it runs great.
Obviously the best thing to do would be replace the cable with the one I just took off the car. But times and heat have "welded" them to the cat.
Would love to leave it disconnected. Put the connector together so it looks like it's fastened.
But what are the effects upon the engine?
 

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But Mad North-Northwest
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11,610 Posts
The square connector is the O2 sensor heater. The sensor needs to be hot to work, the heater helps warm it up faster and also keeps it hot at idle. Seems weird that unplugging that would fix anything...maybe it's shorted internally to the sensor wire circuit or something?

Anyway, with the heater unplugged the emissions should probably be okay? The risk is the sensor could cool off and you might not pass at idle. Would obviously be best to replace the sensor: if you can get an impact wrench and sensor socket on it that might work.
 
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