Troubleshooting OBDII - P0133 (1996 SL2)

[Civic&Saturn]

Hello all. This is my first time posting on Saturnfans, but I've been reading the forums for some time now. Thanks to the regulars here, I've learned quite a bit about keeping a 1996 SL2 5-speed running well (ECTS, throttle body cleaning, etc.). It's over 160,000 miles now. I searched the forums for an answer to the newest question, but found nothing, so I'm posting here to find out how much of a problem I have, and what to do about it.

Recently, the SES light came on and stayed on. A visit to AutoZone revealed a code of P0133. From the AutoZone printout and also from Wolfman's listings of the OBDII codes, it's a slow response time from the pre-catalyst oxygen sensor. The car still drives fine and the mileage is routinely over 30 MPG, so it's not like the car is causing any trouble at the moment, but I'm wondering how to proceed.

Unfortunately, I couldn't find the records on it, but I'm very sure that I replaced that oxygen sensor about three or four years ago, using an aftermarket sensor (probably Bosch). So should I go ahead and put in a new sensor, and if so, aftermarket or OEM? Any other suggestions? Thanks in advance for your help!

[Razorbak]

That code is due to contamination from an upstream source (e.g., fuel, silicone RTV, etc). Don't just replace the sensor until you've determined the source of the contamination and eliminated it. If/when you decide to replace it, go with an OEM part.

[Civic&Saturn]

Thanks for the reply. I'll have to look further to figure out the contamination source. If this info helps any, the fuel filter was last replaced at 147,000, and the air filter and PCV were last replaced at 150,000.

Question: could a throttle body cleaning have fouled the oxygen sensor? That cleaning was done last fall, with the TB still attached to the car. We ran I believe the entire can of carb cleaner through the TB, as it was badly caked up with carbon deposits. But the SES light did not come on back then, only recently.

[Razorbak]

Originally Posted by Civic&Saturn

Thanks for the reply. I'll have to look further to figure out the contamination source. If this info helps any, the fuel filter was last replaced at 147,000, and the air filter and PCV were last replaced at 150,000.

Question: could a throttle body cleaning have fouled the oxygen sensor? That cleaning was done last fall, with the TB still attached to the car. We ran I believe the entire can of carb cleaner through the TB, as it was badly caked up with carbon deposits. But the SES light did not come on back then, only recently.

That's possible. Fortunately, the front O2 sensor is relatively easy to replace yourself, and the OEM part (recommended over aftermarket) is not extremely expensive. You can save yourself some bucks by ordering online from saturnparts.com or saturnparts.net.