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Discussion Starter #1 (Edited)
I purchased my 89 Graduate 3 months ago; the car has 96k miles and I have been replacing parts and hoses in an effort to make it road worthy. I replaced the O2 sensor with a Bosch 3 wire unit. The PO had used a one wire sensor and I know that CA emissions require 3 wires. So I started the car and it ran for about 5 seconds then the fuse at the fuel pump relay blew. I disconnected the plug with two white wires and the car ran ok but a little rich. What would cause the sensor to blow the fuse? I would really appreciate your help, O wise ones. This was originally a California car that was taken out of state for 10 years.
 

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But Mad North-Northwest
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10,524 Posts
The two wire connector is the oxygen sensor heater. These can short internally. Unusual in a new sensor, though.

I think the fuse should be 8A...that what you've got? If so, check the resistance between the two wires in that plug on the sensor, see if it's shorted.
 

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But Mad North-Northwest
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If it's good it's probably somewhere around maybe 4-10 ohms? If it's shorted it'll be <1 ohm.
 
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