need ideas on CEL

daewoomofo · Post by **daewoomofo** » Sun Jul 06, 2008 10:12 pm

2001 lanos sedan 1.6 dohc, 60k miles on engine, 135k miles on car, auto tranny. i had a CEL for the bank one o2 sensor last year, i parked the car for the winter, this weekend i FINALLY got around to changing it (and the cracked exhaust mani) i know i shouldnt have waited this long, but any way... i put a new bosch o2 sensor in the car this morning, running great, went to her moms house, got a CEL, its saying there is no reading from the bank one o2 (the one i just changed). i cleaned the connections at the plug connector, didnt help. any one have any ideas? thanks in advance.

BosnianLanos · Post by **BosnianLanos** » Mon Jul 07, 2008 2:07 am

Bad sensor? Check it with a multimeter to make sure it has a resistance that's within spec. Also, check the wires leading to it for accompanying voltages. Could be cracked wires or an ECU fault.

daewoomofo · Post by **daewoomofo** » Mon Jul 07, 2008 2:21 am

does any one know the resistance specs of a good o2 sensor?i thought about just quick running new wires to the ecu. may be ill try that tommorow.

Daniel · Post by **Daniel** » Mon Jul 07, 2008 9:06 am

You can't check O² sensor by measuring their resistance. Look here how they work.
You should use a common digital voltmeter (10Mohms input) or far better a oscilloscope so you can see the signal while engine is running.
While engine is in "open loop" the voltage is steady. When engine comes in "closed loop" you'll see constant voltage variations. That means ECU is trying to hold the best mixture.
On a single wire O² sensor I pick the signal with a pin through the wire insulation.

Daniel

daewoomofo · Post by **daewoomofo** » Mon Jul 07, 2008 9:39 am

yeah i tried useing a voltmeter to check the resistance, but couldnt get a reading. im gonna try new wireing today. hope thats all it is

daewoomofo · Post by **daewoomofo** » Mon Jul 07, 2008 11:25 pm

ok well i came home from work today, pulled the woo into the garage and started checking connections. i checked the wires that go from the o2 to the black box on the passanger side of the engine bay (has all of the plugs where they go into the passanger compartment) both wires were good, i checked the connection through the plug at the wires, both good, i cheked the wires from the plug to the ecu, good, so my last though was it was a bad o2 from the factory (it happens i know) so i called the local autozone, they had one in stock for $19.99 i probly jumped in my truck and hauled my ass there to get it. when i got it i noticed that this new one is fatter than the new one that i installed yesterday, i went home changed it let the car sit in the drive warming up, all was good, took it for a 15 min test drive and all is good. so.... long story short it was a bad o2 sensor from the fatory. but i want to know why there are 2 different part numbers for the o2 (one for the thick one and one for the thinner one) any one have any ideas? oh and thank you Bosnianlanos and Daniel for the info!

MMamdouh · Post by **MMamdouh** » Tue Jul 08, 2008 7:28 am

maybe they want to emphasize that "size doesn't matter" lol

glad you got that sorted out

MMamdouh

jidasas · Post by **jidasas** » Tue Jul 08, 2008 11:40 pm

I noticed that size issue and if I remember correct the fat one is heated the skinny one not...they list both o2 sensors for up and down stream at advance here...the heated/fat one is the first one and should be a four wire I believe...and the other a two wire?

Jimmy

daewoomofo · Post by **daewoomofo** » Wed Jul 09, 2008 12:25 am

nope both were 2 wire pre-cat o2's. ill get a pic soon