I have a 1997 ford explorer, the check engine light is always on, i chan ge all the oxigen sensors, the maf, the coolant and also i took of the catalitic converters, originally, the code is on is po171 and po172. give me a tip that i can fix it.
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Re: check engine ligt is on
A code P0171/P0172 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak.
There could be a fuel pressure or delivery problem
Possible solutions include:
In the vast majority of cases, simply cleaning the MAF sensor does the trick. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace if necessary
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The recommended repair for both the P0171 and P0174 codes is to clean the MAF sensor. Ensure you use the proper cleaning solution, as there are many that will damage the sensor. Buy a cleaner that is made specifically for MAF sensors. The P0420 code will probably clear up if the MAF sensor clears the other two codes.
What is a CO sensor? Never heard of it. a 1999 OBD2 ford has approximately 1600 possible fault codes most of which can turn on the light. If you dont know which one is turning it on, you are guessing randomly which is expensive and usually unsuccessful. get the code(s) and then diagnose the possible causes. The vehicle you list (99 4L explorer) rarely had injector problems. Much more common were EGR sensor(DPFE) sticking at voltage, evap problems, misfires, and lean conditions due to dirty MAF, or vacuum leaks. get the fault code, or you will not fix the problem.
P0172 - System Too Rich (Bank 1) Basically this means that an oxygen sensor in bank 1 detected a rich condition (too little oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1.
Note: This DTC is very similar to P0175, and in fact your vehicle may show both codes at the same time.
Symptoms: You will more than likely not notice any drivability problems, although there may be symptoms such as a misfire.
Causes: A code P0172 may mean that one or more of the following has happened: The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry. There could be a vacuum leak. There could be a fuel pressure or delivery problem
Possible solutions include: Inspect all vacuum and PCV hoses, replace if necessary Cleanthe MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling Inspect fuel lines for cracks, leaks, or pinches Check the fuel pressure at the fuel rail Check the fuel injectors, they may be dirty. Use fuel injector cleaner or get them professionally cleaned/replaced. Check for an exhaust leak before the first oxygen sensor (this is unlikely to cause the problem, but it is possible)
just bring it to a local advance auto or auto zone they will hook up a code reader this will point you in the right direction it may be an O2 sensor MAF sensor in need of a tune up (plugs, wires, PCV, Air cleaner etc.)
Here is a list of possible causes, hope this helps.
Your vehicle’s computer system has self-testing capability. When the computer senses that there is a problem with one of the components or sensors it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and you need to diagnosed and repaired it. The list of possible codes number in the hundreds. The code itself doesn't tell exactly what component is defective - it only indicates where to look, or what engine parameter is out of normal range. You or a technician will have to perform further testing to pinpoint cause and the proper repair. Even if you reset the light, if the underlying problem is not addressed it will come back on.
Air leaks after the MAF sensor, or leaks in the PCV system
Vehicle running out of fuel or engine oil dip stick not seated
EGR valve gasket is damaged or leaking around the gasket
Exhaust leaks before or near where the HO2S is mounted
Fuel injector(s) not supplying enough fuel
Fuel system not supplying enough fuel during high fuel demand conditions (e.g., the fuel pump may not supply enough fuel)
MAF sensor is dirty (can cause PCM to underestimate airflow)
There are 2 common problems on this concern. 1st maybe a dirty MAF sensor. Remove the MAF sensor and clean it with a good electrical cleaner and air dry or light shop air,then reinstall and do a couple of wide open throttle burst to reset it.
2nd problem and we see alot of this is the orings between the upper and lower intake manifold leaks.You would have to remove the upper intake manifold and replace them.
Check for engine vacuum leaks, use a can of carburetor spray and spray around the top of the engine, pay close attention to the intake manifold, if there is a leak the engine will speed up a little, also the MAF may be defective, cleaning it does not always fix the issue, which is the heated sensor wire no sending the correct signal. My knowledge base? Ford certified Master electronics technician.
those codes are related to your oxigen sensors remplase them and reser te computer by unpluging your battery for 5 minutes
if the problem comes back then to have a false contac on the wire harnes before the oxigen sensors.