Question about 1993 Lexus Ls 400

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O2 sensors how many oxygen sensors are fitted . when should the be replaced , where are they located . The car has done 170000 miles still runs great. THANKS

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  • boyobolton Sep 24, 2008

    thanks triple auto .I,m trying to put an Efie fuel saver module ,will it need 2 Efies or will one lean to the petrol mixture. the Efie is to lean the fuel by tricking the ECU unit to lean the fuel mix. HHO hydrogen generator is fitted & running great but because I cant control the AIR it,s not improving the fuel mpg



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You have four one on each side of engine in exhaust manifold these are your front sensors this is what computer reads the rear ones are past the convertor all they do is make sure the catylitic convertors are doing there job.

If it is running fine i would leave it alone
if you wanna replace them just replace the front ones factory run about 160 each

Posted on Sep 24, 2008

  • TripleTauto
    TripleTauto Sep 24, 2008

    i am not all that familiar with this but you would need two as one reads each side of engine



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1 Answer

Where is the 02 Oxygen Sensor before the cadalic converter on a 2006 Hyundai Santa Fe

Usually these are located on the exhaust manifold or just below the exhaust manifold and you should be able to see it in the engine bay. On V6 engines there will be one sensor on each of the 2 exhaust banks.
You will probably need to remove the engine cover to see the sensors on your exhaust.

If someone told you to replace these because you got a particular fault code I would be wary. A decent scan tool and basic diagnostics can show if the 02 sensor is working or not. Some faults often blamed on an 02 sensor are not due to faulty sensors.

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Why the problem with 02 sensor slow during catalyst monitor

Worn out Converter
Worn out O2 Sensors

Oxygen Sensors get replaced when they fail
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They won't switch much, if their is little oxygen in
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1 Answer

I am getting 13 miles per gallon. what is wrong?

Your O2 sensor (or oxygen sensor) is located on your exhaust system. One placed before your coverter to measure the efficiency of the combustion in your engine by measuring the amount of oxygen left in the exhaust stream. The second O2 sensor is placed after the converter and its job is to measure the effiecency of the converter in filtering out harmful gases in the exhaust by compairing its reading to the sensor paced before the converter. If your O2 sensor has failed it will tell the car's computer that it is running too lean (more air than fuel) by default. Since the computer thinks the car is running lean, it now is adding more fuel to the mixture to try and compensate for the lean condition and will always have a check engine light on. If there is no check engine light on then it probably is not a faulty O2 sensor. Have a qualified technician run a fuel consumption test and go from there.

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This code is related to the oxygen sensor on the drivers side of the vehicle. Most times the sensor just needs to be replaced. If you want to make sure, it is the sensor and not a wiring problem or another condition causing this you would need to preform the following test.

Monitor the bank 2 oxygen sensor (O2) voltage on the scanner. If it's showing lean (under 0.5 V), force the engine rich using some propane or carburetor spray. The O2 should go to 0.8-0.9 V.

If the O2 does not go rich as it should, check the voltage at the O2 sensor on the Black (BK) wire. Perform the same test adding external fuel. If the O2 shows rich when using a voltmeter, re-check at pin 44 Red/Black (RD/BK) wire at the Powertrain Control Module (PCM).

If the voltage at the PCM is low as the scanner shows, but the voltage at the sensor responds and goes rich, locate and repair the open circuit in between the PCM and O2 sensor connector.

If the voltage is stuck lean at the O2 and PCM using a voltmeter, cut the BK wire at the O2 sensor leaving all other wires connected. Re-check the voltage on the BK wire. If it now goes rich when adding fuel, check the RD/BK wire for any continuity to ground and repair the wire as needed.

If the wires test out OK and the O2 sensor does not switch as it should, replace the O2 sensor and retest.

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1 Answer

My check engine light came on and I took it to auto zone and they siad it was the oxygen sensor. I do not have a book on my car and I don't know where the oxygen sensor is located on my car. I have a...

the o2 sensor is located in the exhaust stream-from the exhaust headers, they are usually not more than 18 to 24 inches from the exhaust as it exits the engine-follow the pipes, they are in front of the catalytic converter-if you have a 4 cylinder, you only have one in front of the cat-if you have a v6, you have two. the o2 sensors BEHIND the cat only monitor the efficiency of the cat itself and have no bearing on driveabillity-concern yourself with the front o2 sensors, they control how the vehicle runs-they get 'tired' as they get older, and should be replaced as you get closer to 100,000 miles. It will generally run better and get better gas mileage.

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1 Answer

I need to know what tools to use when replacing oxygen sensor. and where on the car is the oxygen sensor located. Please help

22mm wrench or 15/16" or an O2 Socket

Which Sensor ?

#1 is closest to the engine,before or in the exhaust converter

#2 is the Monitor,in the converter outlet

O2 Sensors get replaced at 100,000 miles or
when they fail

Failing means you have to component test it,
to see if it works correctly.

80% of O2 Codes are Vacuum Leaks or Misfires

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2 Answers

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Hi! You must be frustrated by now! your code is marking that the O2 sensor is bad in bank 1. Did you replace the O2 sensor that is located  before the catalytic converter?  The S10 has an O2 sensor specially made for that cat. its about 30$ That would explain for your blackened spark plugs; your pc on the car is asking for more fuel. GOOD LUCK!!

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1 Answer

Check Engine Light / O2 sensor

Get a print out about the sealant and take it with you, and if you can prove they used a non safe sealant, and it does come up 02 sensors again, it's their fault, I looked in my emissions manual, and the 02 sensors only need to be replaced every 30,000 miles or 24 months, which ever comes first. Good luck.

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1 Answer

F150 floods when cold, runs sluggish when warm

at that many miles its do a timing set

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Bank one is toward the front of the vehicle. Sounds like the heated oxygen sensors have gone bad. The Oxygen Sensors are located in the exhaust pipe and require a special socket to remove and replace.

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