Reoccurring O2 sensor failure
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 27
Likes: 10
From: TX
Reoccurring O2 sensor failure
Hey all!
Have a 2010 base with stg2 cam, and Kooks 1-7/8 headers. Tuned. Runs great...until o2 goes out. Bank 2 upstream goes out every 2-3 months. mv stuck running high (.700+). Works great once replaced. Bank 1, no problems at all.
Run 93 octane. Change oil every 3k (use either redline or driven 5w30). Oil and coolant are clean (no milkshake). No smoke out of exhaust.
Weirdest thing. Frustrating. Anyone have any ideas?
Have a 2010 base with stg2 cam, and Kooks 1-7/8 headers. Tuned. Runs great...until o2 goes out. Bank 2 upstream goes out every 2-3 months. mv stuck running high (.700+). Works great once replaced. Bank 1, no problems at all.
Run 93 octane. Change oil every 3k (use either redline or driven 5w30). Oil and coolant are clean (no milkshake). No smoke out of exhaust.
Weirdest thing. Frustrating. Anyone have any ideas?
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,599
Likes: 4,057
From: Cape Coral, Florida
When it’s stuck high you have to see if the A/F ratio is actually rich or is the sensor “lying” ??…when it’s stuck rich make a large vacuum leak and if it goes lean it’s NOT the sensor…I place one index finger on ground and with other index finger I touch it to the O2 signal wire and I can drive it lean…if it stays rich the sensor is “lying” or you actually have a rich mixture…if the upstream is rich the downstream O2 should be rich if it is actually running rich…if it stays rich disconnect the O2 sensor connector…if it stays high you have a wiring issue…if it goes to 450mv’s you have a bad O2 sensor…I had my 01 stuck lean a few years ago and I fed propane into the engine and did not respond…when I disconnected the connector it went from 100 to 450mv’s…sensor was bad and the exhaust STUNK !!….replaced with Delphi and it didn’t work…then replaced with 3 Bosch and still no good…went with Denso and worked fine !!..if it is running rich it can be a EVAP purge valve issue, or a flaky MAP sensor or MAF…I’d look at those data PIDS when it’s acting up…big thing is seeing if the downstream O2 is rich also !!..and normally the downstream O2 is fairly steady around 700mv’s or so.
Last edited by C5 Diag; Aug 30, 2024 at 11:49 AM.
