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Camry oxygen sensors vs air fuel sensors


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Good day all!

I really need some advice!

When my 2012 Toyota Camry (3.5L V6) started using a lot more fuel than normal, I took it to a mechanic who found code P1135, which according to him means that there is a problem with something called an AIR/FUEL RATIO sensor. I wanted a second opinion due to the high price this mechanic asked to fix the problem, but the next person who looked at my car said there was something wrong with the oxygen sensors.

The second mechanic asked about half of what the first one did to replace the part, but after the sensor replacement the engine light stays on, I use even more fuel, and the engine has lost some power too. When I took the car back to the second mechanic, he said I was driving the car wrong, which is why it is using so much fuel. I know nothing about car repairs, but a friend told me that air/fuel sensors and oxygen sensors are not the same, and that maybe the second mechanic had installed the wrong type of sensor.

Can this happen, and what is the difference between the two types of sensors? Can anyone here help me out with some advice?

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I do come from Toyota family hardcorde, but your issue is too technical for me to make any comment. I am sure someone with more better knowledge can answer.

I can help you with my experience in dealing with a$$ hole mechanics and how to deal with these b@st@rds when they quote: "Do you guarantee your repair in writing in paper?" About 90% a$$ hole mechanic will run away or try to slip in language, that's a sign for you to RUN AWAY and try next mechanic.

Secondly, they should guarantee their repair for at least 1 month - 6 months depending on the type of issue.

Third always ask mechanic to give you old part removed from your car in a box of the new one they installed along with original receipt of the new part installed. Don't be shy on this, as about 50% mechanics add hoax items to inflate the bill.

These advices given to me few years back from an English guy who used to work with me and every time I use these advice I bless him, as this way I can filter too quickly the good vs bad mechanic than wasting my time and money.

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I would ask the mechanic if it's actually a problem with the sensor or is the sensor working correctly and there is something else causing an air/fuel mixture which is causing the error code to show.

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Hi

V6 engines comes with 2 sensor (1 sensor for each bank so you have bank1 & bank2) and mostly he replaced the good one not the bad one in addition to the 3rd sensor on/after the catalytic converter so you have to double check the code (which bank 1 or 2) and you have to clear the code after installation and you need to check the catalytic converter as it may be blocked and holding emissions so the variation of reading for the 3 sensors from standard measures may lead to that DTC.

Good Luck!

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Hi Akeem,

@Technician and @Saleem both make good points. With this type of sensor issue, a mechanic should check the entire control circuit (of which the sensor forms a part) to verify that there are no power supply, resistance, continuity, or other electrical issues present that could influence the functioning of the sensor before replacing the sensor.

However, you mention that you have fault code P1135. On a Toyota this code means that there is a problem in the heater circuit of the pre catalytic AIR/FUEL SENSOR in Bank 1. This circuit controls the heater element in the sensor, which should heat up to about 650 degrees Celsius before it starts to produce usable signal voltages. Conventional oxygen sensors only heat up to about 350 degrees Celsius before they start to work reliably.

If the sensor is not hot enough, it will not produce accurate signals, which could confuse the ECU into commanding unsuitable fuel delivery and timing strategies. One of the symptoms of this is an increase in fuel consumption.

The difference between air/fuel sensors and conventional oxygen sensors is that air/fuel sensors measure the ratio between unburnt fuel and air in the exhaust stream, while oxygen sensors only measure the amount of oxygen in the exhaust stream, which is compared to the amount of oxygen in the atmosphere.

Because of the major differences in the way the two types of sensors work, air/fuel sensors and oxygen sensors are NOT interchangeable, but since they often fit into each other’s screw threads, it is sometimes possible to fit the wrong sensor, even if the electrical connectors do not match. Some mechanics have been known to cut off connectors and to join the wires directly. I am not saying that this is what happened though- it is more likely that the second mechanic fitted a poor quality air/fuel sensor that does not work as well as an OEM part, which could make the fuel consumption problem worse.

I agree with @Technician that the mechanic should check out the heater control circuit on the sensor. This circuit should carry a voltage equal to the battery voltage, but there are many issues that could prevent this, such as a poor ground, damage to the wire, or bad connections.

My advice would be for you to take the car back to the person that swapped the sensor, and insist that he perform a proper check of the heater control circuit. He must also reset the fault memory, and test drive the car with a scanner connected so he can monitor the working of the air/fuel sensor in real time.

Anything else is a waste of your time and money.

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