[solved] Jimny P0134 + P0172 Faults

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.