I got this error on my Skoda Fabia 2006 1.2 Bensin 3 cylinder (engine code BME), the car is shaky on idle like it is missing a cylinder, acceleration is non-linear, and fuel consumption is low at 5L/100km while the factory specs is 6l/100km

The current recurring error code is P0172 System too rich.

It doesn't have a Mass Air Flow sensor, it went 200,000 Km, and I replaced both Oxygen sensors 6 months ago. The oxygen sensors was replaced when I got very high fuel consumption (+30 fuel trim) and P0171 System too lean in MIL.

After the o2 sensor replacement, I started to get P0420 Catalyst efficiency below threshold, but soon disappeared to be replaced with P0172 System too rich (current problem).

The MAP sensor reads 80 (I think) at 80km/h 2500rpm.

Short term fuel trim is almost always in minus between 0 and -8.

Fuel economy great, better than original specs.

Today I got Cylinder misfire (I think it was P0301), which affected the engine greatly, I couldn't accelerate and the engine was very shaky, I turned off the engine and cleared it and every thing went back to where it was.

O2 sensor 1 gives oscillating signal between 0.1 and 0.8v but mostly on the high end of 0.5v, may be due to low refresh rate in the OBD scanner?

O2 sensor 2 gives between 0.1 and 0.3v plus small spikes at 80km/h 2500rpm.

Any idea what could be the reason?

2 Answers 2


The reason was a leaky nozzle. It went well after changing the nozzle on the misfiring cylinder.

I think that the fuel enhance actually worsened or caused this situation.

I used it because I drove the car for very short distances (3km) for long time during winter, that is when the car failed the emission test.

I also had to replace the engine oil that was very thin and increased in volume, because it mixed with fuel, I think.


I am an upcoming diagonstician, in a situation like this I guess you use the manufactured scan tool to diagnosed it first. Besides you only provides one code which is not enough to analyze.

  • Thank you Kayzy, I updated the question with the previous error codes. I originally wrote only one because I'm getting only one code which gets back shortly after I clear it.
    – Aus
    Commented Apr 21, 2017 at 20:01

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