Most oxygen sensor trouble codes are just the beginning. In My experience fuel control components are At Fault. (Mass Air Flow [MAF] sensor uses air flow through it to meter fuel or if you have a Manifold Air pressure [MAP] sensor it uses a vacuum signal to meter the fuel) Generally MAF's are just filthy or tired with possibly excessive resistance (in the wiring) built up from coroded connections or bad connectors, the increased resistance in the sensor circuits will give the ECU out of limit readings which cripple fuel mileage and engine power.
If you have a MAP sensor, possible vauum leaks, as well as increased resistance in the circuit (wiring) and malfunctioning fuel injectors are a common cause for trouble codes from the oxygen sensors. Unfortunately I am not familiar with what type sensor is on your vehicle at this time but figured I'd get you started.
MAF's are constanly flowing air thru them so dirt and corrosion are the culprits here. Spray cleaners are available at part stores but the sensor must be removed from the intake air duct to clean it and not contaminate the air intake with dirt particles which will wreak havoc on your cylinder walls and cause oil consumption.
Some MAF's can be disassembled and the filament like diode looking doo hickeys can be cleaned with alcohol and a Qtip instead of removing the whole thing but not all sensors are the same some are impossible to disassemble without damage. Also, be careful with the skinny wires they are very delicate and bend very easily but if bent its not fatal unless you try too hard to make it perfect again. slight bends wont affect the sensor. Breaking the skinny wires is fatal. 2 TO 4 special security torx drive screws will have to be removed, believe or not these tools are available at most lowbudget Chinese tool carrying retailers. I bought a whole set w/ a driver at Big Lots on the road one time. $2 bucks cheap cheap cheaper than a new sensor at $150.00 plus labor , time, on, and on.
Manifold Air Pressure Sensors (MAP)
MAP's are solid state if its not an obvious wiring problem or vacuum leak or a blockage in the vacuum line. Take it off and stroll down to part store and have it tested. Take your vin nummber with you for proper engine id, they only need one number usually the 8th number or letter counting from left to right. Once it tests good now you can work backwards and check the wiring and connectors for continuity.If the MAP tests bad well there you are.
Whichever Sensor you have the first trouble codes are from the O2 sensors telling you that the fuel mixture is either too rich or too lean. Generally if the code is too rich the MAP or MAF is literally malfunctioning i.e. internally shorted somehow or the TPS (throttle Position sensor)is stuck or dead. but if the code is for a lean condition it can mean that the sensors are having trouble giving a proper reading to the ECU because of the above mentioned causes for each type sensor.
Last but not least are the fuel injectors. When everthing else checks ok these guys are usually the missing link. One injector malfunctioning will give the impression that everything else is wrong. They are the real workhorses of the engine. With the high fuel pressure outputs and the frequency of firing they work pretty hard, the problem is that they are electronic hydraulic cylinders that work off low voltages, so excessive variances in electrical resistance causes them to malfunction and ECU gives off only oxygen sensor codes until they are very bad or just die. Depending on how advanced your ECU's diagnostic abilities are: the codes will appear for high or low voltage signals that are out of range coming from either the right bank of injectors or the left bank, from there, the injectors should be tested idividually to find the bad one. This can be difficult since actual specifications and equipment testing injectors can be hard to find but most franchise part stores can test them.
I hope this wasnt too much info at helps you diagnose whats really going on.
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