[solved] Jimny P0134 + P0172 Faults

Hello everyone,
I have 2009 Suzuki Jimny at 140.000 km (M13A). 3-4 days ago, the engine check light appaered. I scanned with elm327. The faults are P0134 (o2 sensor 1) and P0172(System is too reach).
Today, local  serviceman replaced the O2 sensor and cleared the faults. After 3-4 km later, the engine check light appeared again. I scanned and saw that first P0172 fault appered, and after that P0134 appered again. And i realized that 02 sensor1 voltage value changes too much between 0.2-0.8  but sensor2's voltage value stands still.

-> There is no any performance issue
-> There is no exhaust leakage
-> There is no black smoke
-> Idle is fine

I wonder, that could be because of air filter? In the last maintenance, i have not replaced the air filter. Because it is only 3.000 km and looking clear. Or what else should we look at ?Thank you everyone...
 
 

Firstly, thank you Lambert. I supplied the sensor. As you said, yes it was a cheap sensor, not original. But good news is; P0134 fault has dissappeared, i only have P0172 fault. So i guess that my new O2 sensor is working properly. Sadly, there is no opportunity to take it a professional workshop in my City. Hope we can find the error.

The ECU uses O2 Sensor 1 to adjust the fuel/air mixture (rich/lean) to the correct ratio, but can only adjust the setting so far.

The P0172 code is saying that the ECU has adjusted the mixture as far as it can and it is still showing as rich. Is the O2 sensor you bought designed for your vehicle, they output of these vary quite a bit so it might not be compatible.

I had O2 sensor problems on my other car, eventually I found that you have to remove the battery for 10 minutes to clear the long term fuel trim and let it go back to the default map when changing an O2 sensor.

If it is not a faulty O2 sensor or one that is not compatible with your vehicle, then the fault lies elsewhere.

The MAF sensor could be dirty, over-stating the amount of air entering the system;

If your air filter is clogged and reduced air flow that might give a very rich indication, but you should get poor performance as well, might be worth checking the filter;

A fuel injector may be leaking, putting too much fuel in to the system, or another fuel related issue;

You might have a vacuum leak;

You might have an ignition problem (spark plug/coil) which means that fuel is not buring correctly or timing.

If your engine runs fine with no black smoke, is there a petrol smell at the exhaust? You could take the plugs out to see if they look normal, or soot/oil?

If no petrol smell, plugs look fine, performance and MPG are all fine then most likely it is the MAF sensor over-stating the air flow, so actually everything is normal, but the car doesn't think it is or you have a vacuum leak.

Robin

Thank you Robin,
As you said, yesterday we cleared the air filter and MAF sensor and deleted the fault again. After that I went for a drive on mountain roads about 25-30 km. Thank goodness the fault light hasn't come on yet. I hope I never see it again

Unfortunately, the malfunction light has reappeared (P0172). But i think it's because of the air filter or MAF sensor. Becasue after cleaning the air filter and maf sensor, the malfunction light hasn't appeared for a long time. Normally it reappeared within 5-10 km after cleaning the fault. Also i reliazed that there is a smell of unburnt fuel in the exhaust when P0172 appeare.

P0172 is engine running too rich and the fact that can smell unburnt fuel confirms it is getting far too much fuel.

This suggests it is not the MAF, if it was over-reading, you might get the fault, but not the smell of unburnt fuel.

It could be the air filter, but it will need to be pretty clogged to make the engine run that rich.

After that you are back to the O2 sensor, fuel injector, vacuum leak.

I would take the plugs out and have a look, are they the same, nice and clean or is one or more covered in soot or oil?

Robin

wrote:

P0172 is engine running too rich and the fact that can smell unburnt fuel confirms it is getting far too much fuel.

This suggests it is not the MAF, if it was over-reading, you might get the fault, but not the smell of unburnt fuel.

It could be the air filter, but it will need to be pretty clogged to make the engine run that rich.

After that you are back to the O2 sensor, fuel injector, vacuum leak.

I would take the plugs out and have a look, are they the same, nice and clean or is one or more covered in soot or oil?

Robin

 

But I was wondering then why did it take so long for the malfunction light to come back on after I cleaned the air filter and MAF sensor? Normally it would reappear after 5-10 km, but after cleaning, it took 60-70 km to reappear. By the way, my air filter looks clean and has only done 5000 km, but it's over 1 year old, about 1.5 years old.

And I changed the spark plugs with the originals 5.000 km ago. They were black because they hadn't changed in 130,000 km's.







 

Hi,

I doubt it is the air filter if it is clean and only 1.5 years old.
I doubt it is the MAF sensor if you smell fuel in the exhaust, but it might be. If you have cleaned it, then the only way to be sure is to replace it.

I would still remove the plugs just to see what they look like. Compare with the chart in the following:

www.ngksparkplugs.co.za/technical/technical-spark-plugs/

If they are 'Carbon Fouled' in 5000 Km, then that confirms your Jimny is running very rich.

I just checked the possible causes again......

What causes the P0172 code?

- A dirty mass air flow sensor overstating the amount of air entering the engine which may cause excessive fuel delivery
- A bad oxygen sensor
- A leaking fuel injector allowing too much fuel to enter the combustion chamber
- A faulty fuel regulator, which may not be regulating the pressure of the going to the engine as it should
- A vacuum leak
- A possible fault in the coolant system such as a stuck thermostat or bad coolant temperature sensor
- Worn spark plugs

I think you will just have to work your way down the list. I would start with plugs as they are easy, but I suspect your O2 sensor as this is where it all started.

wrote:

Hi,

I doubt it is the air filter if it is clean and only 1.5 years old.
I doubt it is the MAF sensor if you smell fuel in the exhaust, but it might be. If you have cleaned it, then the only way to be sure is to replace it.

I would still remove the plugs just to see what they look like. Compare with the chart in the following:

www.ngksparkplugs.co.za/technical/technical-spark-plugs/

If they are 'Carbon Fouled' in 5000 Km, then that confirms your Jimny is running very rich.

I just checked the possible causes again......

What causes the P0172 code?

- A dirty mass air flow sensor overstating the amount of air entering the engine which may cause excessive fuel delivery
- A bad oxygen sensor
- A leaking fuel injector allowing too much fuel to enter the combustion chamber
- A faulty fuel regulator, which may not be regulating the pressure of the going to the engine as it should
- A vacuum leak
- A possible fault in the coolant system such as a stuck thermostat or bad coolant temperature sensor
- Worn spark plugs

I think you will just have to work your way down the list. I would start with plugs as they are easy, but I suspect your O2 sensor as this is where it all started.
 

Thank you Robin,
I'll check these out and post feedback here.

By the way, these are my O2 and MAF sensor's graph when idle. Do you think these are normal ?

 

O2 is normal, it should vary like that. MAF is probably normal, my MAF graphs have less changes, but that might be that my system doesn't record as fast as yours.