Experts advice needed : O2 sensor or MAF sensor?

[Zippaboy]

Ok my problem, the car dont idle very smoothly when it is not warmed up or when the weather is very cooling.

Went to workshop A, plug in laptop.
Boss straight away say 02 sensor need to change and quote me a price. As need to order the sensor, i went off without fixing first.

Next day, went to workshop B, the boss plug in a handheld device. Then say is MAF sensor dirty or faulty, he proceed to clean sensor.

Fix MAF sensor back, he say faulty. Must change. Tell me dont believe, you try with the sensor unplugged. Indeed the car was more powerful and run smoother.


So which sensor is the faulty one?

Workshop seems very confident it is the o2 sensor.

But the maf sensor when unplugged really improved alot.

Can anyone advise on this?

[mersaylee]

It’s the MAF if car runs smooth when unplugged.

[QQDreamer]

maf sensor bro. o2 is just measure the amount of oxygen reading to tell ECU how much fuel to inject by the fuel injectors.

 

maf sensor does affect idle rpm readings. if your car have EGR valve. cleaning the EGR valves does helps.  likewise if your car have map sensor, do clean them. workshop dont specifically do all these cleaning for you. it is easy to DIy clean these sensors.

 

all you need is a can of WD40 brand contact cleaner. you just need to know the location of these sensors on your car and socket tools will do the job.

[nazerath]

As what’s said contact cleaner works.

 

It’s very easy to do. If you can find it, you probably can buy from shop n fix it yourself.

[Watwheels]

LoL....some ppl call the Mass Airflow(MAF) sensor as O2 sensor as well, that's why TS is confused.

 

O2 sensors are present on both the air intake and exhaust side.

For intake side they are called MAF sensor. Exhaust side will be called Lambda sensor.The function for both is detecting the amount of oxygen present in the intake air and exhaust gases.

 

For older cars they are able to unplug the MAF sensor and the engine still start and runs. For more modern cars you can't even start the engine if you disconnect the MAF sensor.

 

Some ppl just boh chap and disconnect it until the coe expires.

[Ash2017]

LoL....some ppl call the Mass Airflow(MAF) sensor as O2 sensor as well, that's why TS is confused.

 

O2 sensors are present on both the air intake and exhaust side.

For intake side they are called MAF sensor. Exhaust side will be called Lambda sensor.The function for both is detecting the amount of oxygen present in the intake air and exhaust gases.

 

For older cars they are able to unplug the MAF sensor and the engine still start and runs. For more modern cars you can't even start the engine if you disconnect the MAF sensor.

 

Some ppl just boh chap and disconnect it until the coe expires.

but burn a lot more fuel

[Contipro]

Ok my problem, the car dont idle very smoothly when it is not warmed up or when the weather is very cooling.

 

Went to workshop A, plug in laptop.

Boss straight away say 02 sensor need to change and quote me a price. As need to order the sensor, i went off without fixing first.

 

Next day, went to workshop B, the boss plug in a handheld device. Then say is MAF sensor dirty or faulty, he proceed to clean sensor.

 

Fix MAF sensor back, he say faulty. Must change. Tell me dont believe, you try with the sensor unplugged. Indeed the car was more powerful and run smoother.

 

 

So which sensor is the faulty one?

 

Workshop seems very confident it is the o2 sensor.

 

But the maf sensor when unplugged really improved alot.

 

Can anyone advise on this?

unplug MAF, ECU run at fail safe mode with predetermined air fuel mixture value.

 

 

so likely his diagnosis is accurate.

[Freeder]

Ok my problem, the car dont idle very smoothly when it is not warmed up or when the weather is very cooling.

 

Went to workshop A, plug in laptop.

Boss straight away say 02 sensor need to change and quote me a price. As need to order the sensor, i went off without fixing first.

 

Next day, went to workshop B, the boss plug in a handheld device. Then say is MAF sensor dirty or faulty, he proceed to clean sensor.

 

Fix MAF sensor back, he say faulty. Must change. Tell me dont believe, you try with the sensor unplugged. Indeed the car was more powerful and run smoother.

 

 

So which sensor is the faulty one?

 

Workshop seems very confident it is the o2 sensor.

 

But the maf sensor when unplugged really improved alot.

 

Can anyone advise on this?

Honda cars always kanna this issue..

Most will use OBD to clear the engine check light..

And clear again .. and again,,,

Last heard cost for the new sensor abt $350..

But no guarantee with the engine check light..

[Apple-Tree]

OK. Basically,

 

MAF

 

- Got Thin Wire (Tungsten) and Hot Film type.

- Wire type hardly see or heard of in newer cars lor becos

Prone to breakage

Really need skill to clean it. Thin Wire ma.

 

Most cars use Hot Film lor, it is a ceramic.

It advantage is SELF CLEANING, ya, maintenance free.

How it clean, after a std driving cycle and after the engine is off.  The ECU start housekeeping -90s

For MAF, it will raise the film to about 1000C momentarily and all dust on the film is vaporized.  Or at least it is true for Kia Cars.

 

I never clean my previous Kia Carens MAF for the lifespan of the COE lor.

 

Have not encountered a MAF failure so far for all my rides.

 

O2 sensor

 

It is always prone to failure one, due to it exposure to high temperature - 600~800C.  Or at least that is about the working temperature of this type of sensor.  It is also prone to poisoning by lead compound, sulfide, silicone etc. 

 

The lifespan of O2 sensor is about 120~150kkm. It is not about the sensor detecting O2, it is about how fast, over time, the response time increase. Hence the below symptoms. The test window is as low as 80ms after a lean cycle lor (to charge up the catalytic converter) 

 

Symptoms : Acceleration Hesitation, 'Rough' Engine, High FC, Inconsistency in FC (sometime High sometime Low)

 

I ever for fun change at 150kkm, the engine drive LIKE BRAND NEW - Smooth lor...

 

Since you are ownself wondering now, you might as well buy a cheap OBD scanner and use FREE App.

 

https://www.aliexpress.com/item/33007010660.html?spm=2114.search0104.3.3.7d3d351610uWzZ&ws_ab_test=searchweb0_0%2Csearchweb201602_6_10065_10068_319_10059_10884_317_10887_10696_321_322_10084_453_10083_454_10103_10618_10307_537_536%2Csearchweb201603_52%2CppcSwitch_0&algo_expid=15ed5c54-a831-4ff9-8b4d-5c62df49a239-0&algo_pvid=15ed5c54-a831-4ff9-8b4d-5c62df49a239&transAbTest=ae803_5

 

Got Android ICE Best, You can ownself scan ownself, anytime lor.

 

 

 

[Scholesy]

Honda cars always kanna this issue..

Most will use OBD to clear the engine check light..

And clear again .. and again,,,

Last heard cost for the new sensor abt $350..

But no guarantee with the engine check light..ðð»ðââï¸

For sharing I jus changed an o2 sensor. Oem Bosch brand. 230

[Watwheels]

I usually get from Amazon be it MAF or MAP sensor. Sometimes some of the vendors want to clear stock it can go as low as below US$50. I think for my previous car I bought the MAP sensor for my TC engine for just US$25.

 

Cannot buy locally. The price goes up many times as it goes thru too many middleman.

[Goldenvodka]

Remove the MAF sensor, clean it, fix it back and share if the problem still presist.

 

Once the MAF sensor is out. Take a picture to note down the part number. 

It would be useful 

 

Youtube have many tutorial on MAF sensor cleaning. 

Edited June 4, 2019 by Goldenvodka

[KaKiLang]

I diy MAF cleaning, just make sure use the correct cleaner.

[Johnbrown]

It is the MAF sensor undoubtedly.

[BabyBlade]

Ok my problem, the car dont idle very smoothly when it is not warmed up or when the weather is very cooling.

 

Went to workshop A, plug in laptop.

Boss straight away say 02 sensor need to change and quote me a price. As need to order the sensor, i went off without fixing first.

 

Next day, went to workshop B, the boss plug in a handheld device. Then say is MAF sensor dirty or faulty, he proceed to clean sensor.

 

Fix MAF sensor back, he say faulty. Must change. Tell me dont believe, you try with the sensor unplugged. Indeed the car was more powerful and run smoother.

 

 

So which sensor is the faulty one?

 

Workshop seems very confident it is the o2 sensor.

 

But the maf sensor when unplugged really improved alot.

 

Can anyone advise on this?

 

TS just curious what's spoilt? O2 or MAF sensor?

[Kklim]

I diy MAF cleaning, just make sure use the correct cleaner.

 

Good stuff! Got a can too.