P0171 and P0174 Codes – Don’t change an Oxygen Sensor Before Reading This

So your car’s CEL (always check Engine Light) is on and also you had the codes scanned at a local parts shop. (Or maybe used your own OBD scanner to extract the car faults). Your car or truck has either a P0171, P0174 lean fault code or both stored in the pc, these codes derive from Oxygen Sensor (O-2) readings.

A lean code or codes suggest that there surely is too-much air in the exhaust.

Bear in mind parts shops have staff members having good motives nonetheless they may not have the experience necessary to understand what the problem codes actually imply. These codes derive from air dimensions in the exhaust. A typical blunder with lean codes should change the air detectors.

This may be a very pricey blunder that will maybe not mend the problem. Particularly if both codes are present, considering that the possibility of both O-2 detectors a failure at the same time is extremely not likely.

Likely the main cause is vacuum pressure drip. A vacuum cleaner drip may be caused from vacuum pressure hose, intake gasket and maybe even a leak in the air consumption hose from MAF (Mass Air Flow Sensor).

Pay attention for a hissing noise that could lead you to the origin regarding the issue. Some professionals uses a propane bottle with a hose accessory to assist pinpoint vacuum cleaner leaks.

With today’s computers it is not rather as simple to check on for vacuum cleaner leaks that way considering that the ECU (Electronic Control product) will make up quickly for the included gas and a modification of idle is harder to note.

Oxygen sensor readings may be administered with a scan device while checking for leaks with propane, by shopping for increased readings when enriching the blend. One other way professionals can look for vacuum cleaner leaks is by using a smoke test.

By introducing smoke into vacuum pressure hose on engine, the drip will be uncovered as soon as the smoke escapes from issue area.

Aftermarket air filters that use oil on factor can occasionally damage the MAF. Over oiling air filter may allow some excess to obtain on MAF sensor cable or factor. This might alter the reading, fooling the ECU into witnessing just about air flow therefore changing the air/fuel blend wrongly.

We as soon as worked on a car or truck that could maybe not begin which had an issue with a MAF. When looking at the cable in the MAF, there was a burned bit of rubbish that caused it to be’s method at night air conditioner filter. After washing the sensor the car ran completely.

The ash that has been on MAF sensor cable ended up being altering the reading by enriching the blend plenty that car cannot operate. After talking with the buyer, he said air filter ended up being simply altered. This was clearly when some rubbish got into the air intake hose that decided on hot wire regarding the MAF.

Fuel Pressure could also cause a lean condition. If gas filter is blocked or perhaps the gas pump pressure is reasonable, there might be higher degree of oxygen in the exhaust also. In most cases though, the ECU will make up for the paid down gas amount. So this is one of the least likely factors that cause a lean code.

Eitherway, if want to get technical data from ECU about this code and many others, just plug a scantool to car and you’ll see all the faults reported..

P0171 and P0174 Codes – Don’t change an Oxygen Sensor Before Reading This
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2 Responses to P0171 and P0174 Codes – Don’t change an Oxygen Sensor Before Reading This

  1. P0171 suggested causes:

    Ignition misfiring
    Intake air leaks
    Lack of fuel Faulty
    Mass Air Flow (MAF) sensor
    Incorrect Positive
    Exhaust gas leaks
    Crankcase Ventilation (PCV) hose connection
    Faulty front heated oxygen sensor
    Incorrect fuel pressure
    Faulty fuel injectors

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