Testing O2 sensor...blew a fuse??
11-09-2009, 12:56 AM
#1
Three Wheelin'
Thread Starter
Testing O2 sensor...blew a fuse??
Thought i'd see if someone can put sense to this...I've been getting lousy gas mileage on the last couple of tanks and thought possibly my O2 sensor was failing with my rich condition I've been experiencing. I was testing the O2 as per Clark's and accidently touched both connections in the plug with the same probe on the meter, didn't think anything about it as the engine continued to run, then seconds later it started to run rough and then died and wouldn't start. It was getting spark, just sounded like no gas was getting there...checked the DME relay jumping the 30 & 87b terminals and the fuel pump didn't start up??? mmm for a moment I was thinking...did I fry the DME @#$%. Checked the DME fuse and it was blown!
Could this happen by making contact with the two terminals on the O2 sensor?
Could this happen by making contact with the two terminals on the O2 sensor?
11-09-2009, 05:18 AM
#2
Lazer Beam Shooter
Rennlist Member
Rennlist Member
Mnnhmm.
The 3 wires on the oxygen sensor, 2 of them are white. One of the white ones connects to a ground, the black one connects to pin 24 on the DME. The second white one gets power whenever the DME is running.
The white wires are the wires for the heater element on the plug. You could run without those actually and the O2 sensor will still work (just wont work as quickly when the car is cold). Contacted 2 wires coming off of the DME with either a ground or each other. This will blow the fuse.
The 3 wires on the oxygen sensor, 2 of them are white. One of the white ones connects to a ground, the black one connects to pin 24 on the DME. The second white one gets power whenever the DME is running.
The white wires are the wires for the heater element on the plug. You could run without those actually and the O2 sensor will still work (just wont work as quickly when the car is cold). Contacted 2 wires coming off of the DME with either a ground or each other. This will blow the fuse.
11-09-2009, 06:16 AM
#3
Rennlist Member
Mnnhmm.
The 3 wires on the oxygen sensor, 2 of them are white. One of the white ones connects to a ground, the black one connects to pin 24 on the DME. The second white one gets power whenever the DME is running.
The white wires are the wires for the heater element on the plug. You could run without those actually and the O2 sensor will still work (just wont work as quickly when the car is cold). Contacted 2 wires coming off of the DME with either a ground or each other. This will blow the fuse.
The 3 wires on the oxygen sensor, 2 of them are white. One of the white ones connects to a ground, the black one connects to pin 24 on the DME. The second white one gets power whenever the DME is running.
The white wires are the wires for the heater element on the plug. You could run without those actually and the O2 sensor will still work (just wont work as quickly when the car is cold). Contacted 2 wires coming off of the DME with either a ground or each other. This will blow the fuse.
11-09-2009, 08:28 AM
#4
Addict
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Hidden 944 feature - the O2 sensor heater circuit is on the same circuit as the fuel pump - not noted in the fuse box lid!! So if you crossed the O2 heater wires you blew the fuel pump fuse and thats why it quit running and won' start!
11-09-2009, 10:58 AM
#5
Three Wheelin'
Thread Starter
ahhhh...I looked at the wiring diagram and couldn't find where this connection occurs, but it must.
Replaced the fuse and it fired right up.
Thanks guys!
Replaced the fuse and it fired right up.
Thanks guys!
11-09-2009, 06:21 PM
#6
Pro
Very timely info for me, I didn't know that either. I'm replacing my O2 sensor with a far less expensive, generic Bosch 3-wire sensor from Paragon (whenever I get time for it - it's just completely disconnected for now and the car runs better than it ever has! But unfortunately it's not driven much.) - something relatively new Paragon is offering to help save $$ on maintenance costs. Requires splicing the new O2 sensor into the old connector, comes with the wire splicing parts. I was wondering what the third wire was for. At least now I'll know what I did wrong if it doesn't work well cold (which I will find out quickly in Chicagoland).
