O2 Faults
 

About 8 mo. ago I got my car. One of the things I did is replace the O2 sensors since it was giving me a bad reading for one. I replaced them all with USOS-4000 Universal Sensors. Now it is reporting bad O2 sensors again. This is the breakdown of what has been happening:

7/29/09 - P0139 (replaced)
8/13 - P1118 (replaced)
8/30 - P1502, P1115, P1117, P1119 (replaced both pre sensors)
current - alarm has gotten wet and can't proceed but before that happened CEL came on once again

The thing that concerns me is that on the Durametric website, it says in troubleshooting '00 986s that when multiple O2's go off, it can mean that I have a bad MAF or air leak. That P1502 is suspicious. I had that code before and it turned out that my brake booster hose had a leak. Replaced it and CEL went away. This was about 3 mo. back. What do you guys think is going on?

You used the wrong O2 sensors
 

and didn't crimp them correctly and so are giving bogus signals to the ECU is my guess.

Bosch makes the ones Porsche buys and Bosch has multi-million dollar machines that do the crimp and then test. I've used them to replace both my pre-cat sensors.

When my CEL kept coming on for various 02 sensor faults the first thing I tried (based on what I'd read in these forums) was to thoroughly clean the MAF with electrical contact cleaner and Q-tips.

No problems since then and that was almost a year ago. Probably worth a try for a few dollars worth of cleaner, although you do need some tamper proof star (torx) bits to get at the sensor.

don't know if this helps, but I have a set of 4 OEM sensors that had about 40k on the (no codes when the engine died)....you're for free if yours interested.

So you disconnected, cleaned, and then reconnected the MAF and then cleared the codes on the O2 and haven't gotten anything back? I may try that. I find it hard to believe that I didn't crimp them correctly. I was actually using posi-lock connectors which are better anyway. This is something that happened out of nowhere so I just don't see how all of a sudden all the O2 sensors went bad or lost a electrical connection at once.

Yes, the MAF has two 'mirrors' inside which I carefully cleaned -being sure not to leave any cotton fluff from the Qtip inside.

Reconnected everything back and cleared the codes with the Durametric gizmo and, although I couldn't tell any difference in how the engine runs, I've not had the CEL since. Before cleaning the MAF it would come back on every 20 to 30 miles or so.

Interesting. I will have to try that. Did you ever get the p1502 error (idle air control)

I wouldn't touch the MAF surfaces
 

with a q-tip. Rather use MAF cleaner spray and be careful not to touch any of the surfaces which could be doing the measuring of the airflow, rather just touch the plastic. Shake to dry. These things are expensive and I've never run across a generic one, rather just the Porsche branded and OEM maker.

Just been looking at my logs and the codes I got were 1123 and 1125, so no on the 1502.

I was going to replace the MAF if cleaning didn't work, so wanted to ensure that it was completely clean. Don't think I understand what the concern is with using a Q-tip soaked in cleaner, but sometimes I guess it pays to play it safe.

Ignore your MAF. These codes are not related.

P1502- Throttle jacking spring test-
Clean the contacts to the throttle jack and be sure the harness is not damaged. For more info: http://www.renntech.org/forums/index.php?act=Search&CODE=show&searchid=300de68904 ded095af73b8701e48489d&search_in=posts&result_type =topics&highlite=%2Bp1502

P1115,p1117,p1118,p1119- O2 sensor heating below threshold.
Bad sensors, wrong sensors for your car model, mis-wired sensors, damaged wire harness. You currently have no working O2 sensors so no monitoring of your mixture. This can damage your cats and potentially your engine over time.