jmrosen

Recently had some maintenance done on my 1982 5 speed. 70K miles (original owner). New alternator, fuel pump reply, cooling fan thermal switch, cooling fan relay and new radiator.

Car finally running cooler that it has been in the Florida heat and all was fine for a week or so and then the other night on the way home after a little aggressive driving the Warning Light (!) started flashing with low oil level indicator along with OXS light illuminated. After about 1 minute all flashing and illuminated warnings stopped and I drove the last 1/4 mile home without issue. Checked oil level, it was full. Next day I drove and noticed that just the OXS light started to light up. The Oxygen sensor was changed about 15K miles ago and should, I'm told, only light up when it is at 30K and the OXS counter throws the light. Any idea where to start looking? I have never had warning light issues in the past.

Thank you in advance for any help!

WallyP

The Oxygen Sensor warning light has nothing whatsoever to do with the functioning of the oxygen sensor.

Porsche didn't know how long the sensor would last, so they put a counter on the speedometer/odo input to set the light every 30,000 miles. The sensor can last a lot longer than that, unless it is poisoned by leaded fuel, RTV fumes, etc. The sensor warning system has not a clue as to whether or not the oxygen sensor is working...

Just unplug the counter under the passenger door sill cover, and drive on...

jmrosen

I understand that. The OXS light lit up when the low oil level light started to flash and then both of those lights cleared about a minute or so later. Next day just OSX light and then it cleared. The OXS counter was reset about 15K miles ago and as that counter is the only reason for the light, it's way too soon for it to be on as a reminder to change the OSX. That, and it coincided with the low oil level makes me think this is some kind of short. My oil level was right to the full line on the dip stick and all at once that light AND the OXS went on, then off. Any thoughts on where to look for the problem?

WallyP

Power flows from Fuse #12 to the main power bus in warning light section of the instrument panel.

Power flows from the bus thru the Oxy Sens light to the counter unit, where it is grounded when the counter reaches its set point.

Power flows from the bus thru the Oil Level light to the 22SW terminal of the Central Warning Computer. Power flows from the Central Warning Computer terminal 10SW to the Oil Level Switch. When the oil level is low, this switch grounds the wire, and the Oil Level Light is turned on.

I see no likely connection between the two warnings.

jmrosen

No likely connection? The OXS light and the low oil light both came on and went off at the same time. Never had either light go on in 30 years. Obviously there is a connection, somewhere . . .

WallyP

That means that there is an unlikely connection somewhere - nothing obvious in the wiring diagram...

jmrosen

Do you think it has anything to do with the new alternator, voltage issue perhaps?

Dave Eschmeyer

WallyP what if my oxygen sensor light starts to light dimly, then brighter, then goes out... then back on dim->brighter...

do i have a ground issue on the counter? My speedo says 49k so im not due for the light to light,... unless the last owner switched out the spedometer...

Hobibill

Was there a resolution to this? Mine is doing the same thing. Would just like to reset the counter rather than disconnect it.

Dave Eschmeyer

the issue went away on its own for me.