I have a 2004 chevrolet 1500 Z71. I have a check engine light I am getting codes for the MAF sensor, the O2 Sensor it was the heating element code. I don't have the codes on hand. But any way I checked the MAF sensor all elements are intacked, cleaned it with some non residue electrical cleaner. I also removed the fwd and aft O2 sensor both were clean as could be. Cleaned them anyway with same cleaner. Checked out the vac lines to the intake, and intake manifold and started the truck and sprayed around intake manifold to check for leaks. The truck has high flow aftermarket cats that are 30,000 miles old so they aren't cloged. The truck runs fine, I haven't had any issues other than I had to put a new alternator on it today. I just cannot stand a check engine light. Any suggestions.
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Re: O2 check engine light
U may indeed have a faulty MAF or O2 sensor, the way to tell if the MAF or a vacuum leak is at issue is that both O2's will code lean, if only one codes lean then it is most likely just a faulty O2 sensor, I don't have your codes but this is the way we do things at the dealer for problems like yours. Remember the O2's are before the Cat's., after the Cat's they are called Cat efficiency monitors in the book.
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Re: O2 check engine light
I have a 1999 Silverado K1500 that started doing the same thing....the codes told me nothing...another wrench told me I needed a $900 head gasket repair, another told me I needed a $290 Injector replacement........what I had forgotten was that I ran a can of HEET through my tank..when that gas was gone so was the problem.
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It isn't the PCM. You most likely have a bad, dirty, or plugged mass air flow sensor. The cam position sensor is also a notorious failure, so that's a possibility. Most likely it is that the MAF sensor has caused an evaporative emissions systems error, and the engine timing is one of the things the PCM tries to adjust to meet compliance with the air/fuel/spark requirements to run cleanly. If it can't adjust the timing enough to correct it, then the cam position sensor will attempt to operate out of its limits, setting that code. Check your MAF sensor. Clean it or replace it, reset the codes, and drive it. If there is another problem, it will tell you.
There could be too many reasons. Air filter, MAF sensor, O2
sensor, spark plugs, injector and so on. Simply, get the codes read if the
check engine light is flashing. Most repair shops do this for free.
Yes your o2 sensor could do this, it's most likely the closest one to the motor, the first one that is coming from the engine. That is the one that reads the exhaust gas, it then tells the computer how much gas to mix in with the air. It also could be your MAF(mass air flow sensor) connect to your intake.
*PS I have the same motor, wouldn't hurt, might get better MPG.
If your O2 sensors are malfunctioning, the main symptom would be that the Check Engine light will come on. On some vehicles, an O2 sensor circuit shorted to ground can cause a no-start problem.
If the "Check Engine" or "Service Engine Soon" light is on and there is a code for the O2 sensors, I would like to also advise you that many O2 sensor codes are not caused by the O2 sensors themselves. In many cases, the O2 sensors are only REPORTING the problem. for example, a code P0171 "Oxygen Sensor Lean" code is rarely ever caused by the O2 sensor. It is usually caused by a vacuum leak or a failed Mass Airflow sensor (MAF) or Manifold Absolute Pressure sensor (MAP) or a bad fuel injector. In these cases, repairing the real reason that the engine is running lean will fix the O2 Sensor code without replacing the O2 sensor.
besides the heated oxygen sensors being faulty, lean mixture codes also refer to intake/exhaust leaks ( cracked flex section of exhaust pipe at manifold , low fuel pressures /pump, faulty injectors , MAF/VAF,wiring and ECM
Hi, the o2 sensor codes may be a result of the maf. If the mass air flow sensor does not show the correct flow, the fuel mixture could be accomodating accordingly, resulting in a rich, or lean condition, setting codes. If there is a plugged, or restricted air filter, or a piece of debris on the sensor, this could cause a faulty reading. Also, make sure the air duct is tight at the throttle body, and the maf sensor is tight. Last, if you use a K&N filter, that uses an oil charge, there may be oil residue coating the maf sensor, causing an issue, or just a faulty sensor. At any result, I feel you should fix the maf issue, before the o2, as this is the order of operations, and you may not need o2 sensors. Good luck...Coop
P0137 o2 circuit low voltage bank 1 sensor 2 --o2 sensor after the cat converter -check for faulty o2 sensor -short or open circuit exhaust leak near sensor or plugged cat converter ----P0171 and P0174 -system too lean bank 1--and system too lean bank 2 they are usually from the same problem which can be caused from the o2 problem but check ur maf sensor connections and or clean if necessary[carb cleaner] vacuum leak downstream from maf sensor also inspect pcv lines
Go to your local autozone where they can hook up their scan tool for no cost to you. Be sure to write down the codes and definitions of the codes and repost if you don't know where to go from there. Also, I don't recommend replacing parts just because the guy at autozone tells you that's what you need (ie, they will tell you to replace oxygen sensors if an o2 sensor code comes up).
you have to know what the code is that your truck putting out your truck has 4 O2 sensors. the trucks computer is smart and the code will tell you witch one is bad but if you replace just one the next one on the same exhaust pipe will probley go bad so its safe to replace all four. the draw back to replaceing all of them is thay cost about 80 bucks for one ACDelco O2 sensor. It has to be done before it will pass Emissions. not a hard part to change about a 7/8 open end wrench will take it off. have fun.