Another O2 sensor saga...

[soundguy]

97' Base, 104K, Tip.

June 3rd,
CEL light comes on. Durametric shows-
P0420, P1102, & P1107.

I repalce the 2 pre cat O2 sensors, which I had planned on doing anyway as maintenance.
Reset codes, drive 75miles with no CEL. Just as I arrive home CEL light back on.


Now I have P1115 & P1119 ( heating power ahaed of Cats on both banks.
Feeling a little helpless at this point I take car to local Porsche shop. After $515 of diagnostic labor, they say the 2 O2 sensors are NG, and that there are a lot of counterfeits out there, and I probably got 2... I am skeptical but trust these guys. I'm attaching receipt with notes from shop.

I buy 2 more sensors from a different source and install them. Reset fault codes. Go for another 50 mile drive and by the time I am home the CEL light is back on. Now back to P1102 & P1107 again.
( O2S heating power ahead of cat on both banks exceeds limit value.)

I have to solve this w/o spending another $500 in diagnostics. Electrical issues not my forte, and I fear something crazy in the harness at this point.

MAF sensor? Vacum leak? Any thoughts and suggestions deeply appreciated.

[bcrdukes]

Which brand of oxygen sensors did you purchase?

[JFP in PA]

P1102 and 1107 indicate the heating resistance of the sensors is too low. Disconnect the O2 sensor harness connector and check the resistance between pins 1 and 2 on the sensor, you should see 1.8 to 2.5 ohms at room temperature. If you get those values, your harness from the sensor to the DME has a wiring issue.

[soundguy]

Hey JFP, I was hoping you'd pipe in. Thank you for your expertise. I will check those values tomorrow and report back.

They are Bosche 13806 O2 sensors with the Porsche connector.

[mikefocke]

Exactly what O2 sensors are you buying? Porsche brand from a dealer? Bosch? Part numbers please.

[soundguy]

Bosch 13806, from FCP Euro.

[soundguy]

Disconnected sensor, and I'm seeing values closer to 2.7-3 ohms on pins 1 & 2, which on my sensor are the 2 white wires, the heating wires as best as I could determine.

Are you still thinking sensor harness point to DME as the culprit, and if so how would I proceed?

Thanks, Rick

[JFP in PA]

You need the wires that go to those pins traced back to the DME harness pins, looking continuity, shorts, or breaks.

[soundguy]

Could be above my pay grade, but I will give it a shot. Thanks Jeff.