Rain affect O2 sensors?
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,147
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From: San Antonio Texas
Rain affect O2 sensors?
Last weekend I got stuck driving my LT4 about 600 miles in the rain/fog/mist. I rinsed off the outside dirt and put it away for later. It's been in the garage till last night, and drove about 20 miles and got a check engine light.
Checked the codes and it's the front passenger sensor "low voltage" reading. Could water in the connector cause this? I replaced all 4 sensors in July '08 and I would think they would last longer than that! I've got fresh EVERYTHING. new Opti, wires, plugs & Bosch III injectors. The car runs great and has been getting good mileage (I keep close watch and there has been no change). Moisture somewhere?
Checked the codes and it's the front passenger sensor "low voltage" reading. Could water in the connector cause this? I replaced all 4 sensors in July '08 and I would think they would last longer than that! I've got fresh EVERYTHING. new Opti, wires, plugs & Bosch III injectors. The car runs great and has been getting good mileage (I keep close watch and there has been no change). Moisture somewhere?
Le Mans Master
Joined: Jul 2007
Posts: 5,043
Likes: 8
From: Tampa Florida
Not sure the moisture would affect the connector since it shoud be "weather" resistant with the stock connector but it is worth a quick look. It is possible that your fog slightly affected the A/F ratio in the pipe but I doubt it shifted it enough to cause an issue. You might look at the manifold on that side to see if you have an "air" leak/loose hardware that is sucking the ambient oxygen in and affecting the sensor.
Le Mans Master
Joined: May 2006
Posts: 9,226
Likes: 9
From: Irvine Ca
Sure on a ~20 year old vehicle.
When My wires broke, (on another spot but low in the engine bay ) when I stripped back the housing...it was green inside.
Also, look where your wires are hanging. My O2 wire was contacting the exhaust and I think I was getting a weird signal to the computer...I moved the wire away and it seemed to run a bit smoother.
When My wires broke, (on another spot but low in the engine bay ) when I stripped back the housing...it was green inside.
Also, look where your wires are hanging. My O2 wire was contacting the exhaust and I think I was getting a weird signal to the computer...I moved the wire away and it seemed to run a bit smoother.
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,147
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From: San Antonio Texas
Just pulled the sensor and it looks fresh inside. The plug and harness though is a mess of oil & sand/dirt. I've got a little oil leak somewhere and it has made a mess back by the starter and along that side of the engine. I'm going to clean as good as I can under there and check the harness for corrosion in the plugs. everything else looks OK. The sensor tip wasn't even sooty so it's not running so rich as to foul the plugs or anything. Maybe it's just a bad sensor, but I have my doubts about that.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
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From: Kempner Texas
Thread Starter
Team Owner
Joined: Feb 2006
Posts: 23,147
Likes: 117
From: San Antonio Texas
I cleaned out the harness plug by the starter and shot WD40 into each pin hole. I then followed that with a blast of air from my compressor to make sure all the water & dirt was out of there. Put a smear of 'Right Stuff' gasket sealer on the top side of the plug where the wires enter, to make sure no more water could get into the plug from there, and put some Sil-Glyde on the weather pack seal when I reconnected the new O2 sensor.
Fired it up and about 1/2 way around the block, the check engine light turned OFF.
Don't know if it was all the junk that got in the plug or if that sensor just crapped out, but it seems to be OK $63 bucks later. I either have a spare O2 now or one to warranty if it goes bad within a year. I'm going to try my best to stay out of the rain now cause I've got a mess to clean up under there!
Fired it up and about 1/2 way around the block, the check engine light turned OFF.
Don't know if it was all the junk that got in the plug or if that sensor just crapped out, but it seems to be OK $63 bucks later. I either have a spare O2 now or one to warranty if it goes bad within a year. I'm going to try my best to stay out of the rain now cause I've got a mess to clean up under there!
