Replaced my 02 sensors myself - 986 Forum - The Community for Porsche Boxster & Cayman Owners

RandallNeighbour · 02-06-2006, 10:27 AM

Some of you are really good turning a wrench. I'm doing it only because I don't want to give all my money to Hans, my mechanic.

So, I jacked up my car, located all four sensors, went to Pep Boys, bought an 02 sensor offset socket, and did the job in about 40 minutes. Hardest part was threading the new ones in and not getting the tips dirty.

No CE lights after a long idle, multiple on and offs, and spirited freeway driving! Just in case you're wondering, it did not increase my engine's performance according to my butt dyno.

I'm thinking I'll get better fuel economoy though. The old ones had 94k on them and were very dirty.

I must say that this is a job that just about anyone with a jack, a jack stand and an hour can do themselves.

Dealer Quote: $1220 ($280 for the sensors and an hour of labor)

Actual Cost: $485.99 (Sensors - $119 each; Sensor socket $9.99)

Feeling I had inside after doing it myself and saving all that cash?: Priceless!

MNBoxster · 02-06-2006, 10:51 AM

Hi,

Good for you! Agreed, the feeling from doing it yourself is priceless.

One Tip which may help - Disconnect the Battery for 5 min. and then reconnect it. This will clear the DME's Adaptive Memory so it can learn again. This may add some performance as it adjusts to the new Sensors (Car will idle/run ********************ty for the first few minutes/miles, but will improve as the DME learns).

You may not get a MIL with older O² Sensors because the DME can compensate for their diminished operation, but that doesn't mean that everything's running optimally. I would suggest to others that 94K is too long to be on the original O² Sensors. These do fail progressively, meaning that you get increasingly lower performance and MPG. Bosch (OEM Supplier of Porsche O² Sensors) states the Life of their Heated O² Sensors to be 60k mi.

Interesting about the costs, but I can't make the math work. I assume you mean the Dealer wanted $280/O² Sensor, then an hour Labor. $100/hr. Labor Charge seems quite reasonable.

One good way to look at the money you saved is that your next set of Tires is now essentially FREE!! Gotta LOVE that!! And, you're not through. Bosch estimates that fully functional O² Sensors will save the average driver $100/year in Fuel as well!

Happy Motoring!... Jim'99

RandallNeighbour · 02-06-2006, 11:05 AM

Jim, yes, the dealer wanted $280 a sensor plus an hour of labor at $100... he said that was a good deal for the labor, by the way, and I was being "cut a special price."

It's hard not to laugh sometimes.

The same dealer wants $850 for a MAF and an hour installation as well.

When that goes out I'll replace it myself as well... and it's a lot easier from what I read.

Thank you for the tip about disconnecting the battery and the anticipated rough idle as the DME works it all out. I will do that tonight and see what difference it might make on the old butt dyno

What's "MIL" stand for, anyway?

Tires - yup, I did save enough for new rubber, which I need, but I'm holding out to put new rubber on new 18's like Jeph did... those aftermarket carreras with the proper boxster offset at 995.00 are just too sweet of a deal to pass up!

MNBoxster · 02-06-2006, 12:27 PM

Quote:

Originally Posted by RandallNeighbour

Jim, yes, the dealer wanted $280 a sensor plus an hour of labor at $100... he said that was a good deal for the labor, by the way, and I was being "cut a special price."

It's hard not to laugh sometimes.

The same dealer wants $850 for a MAF and an hour installation as well.

When that goes out I'll replace it myself as well... and it's a lot easier from what I read.

Thank you for the tip about disconnecting the battery and the anticipated rough idle as the DME works it all out. I will do that tonight and see what difference it might make on the old butt dyno

What's "MIL" stand for, anyway?

Tires - yup, I did save enough for new rubber, which I need, but I'm holding out to put new rubber on new 18's like Jeph did... those aftermarket carreras with the proper boxster offset at 995.00 are just too sweet of a deal to pass up!

Hi,

MIL = Malfunction Indicator Light pretty much the same as CEL...

Happy Motoring!... Jim'99

xclusivecar · 02-06-2006, 02:13 PM

To note: Finally had the 4th sensor replaced under warranty last week and immediately noticed the idle dropping rather quickly on cold start now. Before the car would idle at 1200 RPM for about 2 minutes until dropping to 800 RPM. After new O2 sensors were installed, the idle dropped to 800 RPM after maybe 20 seconds! Is this a matter of the sensors heating quicker than before and therefore telling the computer to relaxe the idle? This alone is probably where the savings in gas comes in!?!?!

MNBoxster · 02-06-2006, 02:28 PM

Quote:

Originally Posted by xclusivecar

To note: Finally had the 4th sensor replaced under warranty last week and immediately noticed the idle dropping rather quickly on cold start now. Before the car would idle at 1200 RPM for about 2 minutes until dropping to 800 RPM. After new O2 sensors were installed, the idle dropped to 800 RPM after maybe 20 seconds! Is this a matter of the sensors heating quicker than before and therefore telling the computer to relaxe the idle? This alone is probably where the savings in gas comes in!?!?!

Hi,

Yes that's certainly part of it, but not the whole story. If the O² Sensors aren't operating optimally, the electrical signal they generate is off-spec. The DME reacts in several ways simultaneously affecting the FI, Ignition Spark.

Heating elements with a reduced efficiency delay the onset of the Chemical reaction between the O² in the exhaust and the Ceramic disc in the Sensor (the Ceramic must be at least 650°F for this reaction to take place).

But, in addition to this, running cold longer allows combustion byproducts to condense on this Ceramic reducing the surface area it has exposed to the exhaust gasses and any unburned O².

It may sound insignificant, but Bosch states it useful life for Heated O² Sensors as 60K mi., but only 30k mi. for Unheated ones, pretty big difference for just having a Heater Coil in one, while the other relies on the Exhaust Gas Heat alone to raise it to operating temp.

Once this inaccurate signal degrades to a certain point, the DME goes into a Default MAP which runs Richer than normal because it wants to insure against running Lean, so more fuel is actually used. According to Robert Bosch, this can amount to $100/year for the average driver.

Happy Motoring!...Jim'99

deliriousga · 02-06-2006, 05:31 PM

Way to go Randall!! It sure feels good to save 1/4 of the cost of a new set of wheels, eh? :dance: