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2003 Skoda Fabia P0170

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New User

Jul 1, 2020, 1:45 PM

Post #1 of 6 (2270 views)
2003 Skoda Fabia P0170 Sign In

Hi all,

I have a 2003 Skoda Fabia 1.2L AZQ with around 110k driven that has been giving me a P0170 error. I tried to diagnose myself but haven't been able to pinpoint the issue, I would appreciate any suggestions on what could be root cause and/or explanation what conditions actually trigger a P0170 warning. First off, apart from the warning light & error code there's no indication there's anything wrong. Car drives as before the light, not misfires or loss of power or odd sounds. Temperature & consumption is fine.

Things I've checked so far:
- Vacuum leaks: I think there's only one vacuum hose from the engine to the brake, I inspected the hose and didn't find any crack and when I removed the hose it make a nice wine bottle opening sound. Also my brake pedal becomes stiff/resistant when I pump it with the engine turned off.
- Pre-cat O2 sensor: Shows as O2S11 mA reading in my scanner. alternates between positive and negative when on the highway in cruise control. Seems to be functioning as intended.
- Post-cat O2 sensor: Shows as voltage in my scanner. On highway in cruise control seems to be more or less around the 0.450 +/- 0.2. Changes less drastically and frequent than pre-cat.
- EQ_RAT11: at highway in cruise control around 0.96-1
- MAP Sensor (Car doesn't have a MAF I believe): indicates around atmosphere when car is turned off. Varies while driving related to throttle amount.
- Long term fuel trim: around 2.3% on highway on cruise control.
- Short term fuel trim: Alternating between -7 & + 7% on highway on cruise control. Rapid changes. These last two could be some indication I suppose but the general rules of thumbs I found online indicated that you want the short term fuel trim to be within 10% and long term withing 3% or both added together less than 10%, so by that criteria it should be on the good side still.
- Catalytic converter: O2 sensors readings don't give an indication that it's not working, I check inlet & outlet temperature. Outlet temperature is around 50-80°C hotter than inlet. The al knowing internet also suggests that this is OK. Was difficult to measure the inlet temperature so this measurement might be a bit off but it's the best I can do right now.

Readings from the scanner on the highway:
Load_PCT: 39.6%
ECT: 86°C
SHRTFT1: 0.6%
LONGFT1: 2.3%
MAP: 55 kPa
RPM: 3630 /min
VSS: 108 km/h
IAT: 54°C
TP: 19.6%
O2B1S2: 0.695V
mil_dist: 490 km
EQ_RAT11: 0.976 -
O2S11: 0.086 mA

Please let me know if there's anything else I could check before I hand the car over to a repair shop. Thanks in advance!

Ps. Some history that might be relevant. I while back I had a broken coil in my second cylinder while driving on the highway. After this happend I would get a P0138 (02 sensor 2 high voltage), P0420 (Catalytic converter efficiency below treshhold), and P0170 error. The warning lights would go on and off every 50-100 km or so and again no symptoms in the car expect the warning light. I figured that due to the misfires of the broken coil some unburned gas entered the cat & exhaust system and instead of replacing parts I would first try to clean the system with Hydrogen cleaning (Hydrive in Denmark). The warning light disappeared after the cleaning but popped up again after 450km. I deleted all error codes to see which one would return and how long it would take. This time it took 650km before the light turned on again and only P0170 returned. The cleaning definitly changed the frequency of the light turning on and about 2000 km since the cleaning I only have the P0170 code. Right now I think the P0420 & P0138 issue has been solved but there's another cause for the P0170 light to turn on.

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 1, 2020, 2:36 PM

Post #2 of 6 (2267 views)
Re: 2003 Skoda Fabia P0170 Sign In

First off we don't have that car here in the US so we have nothing specific to that car.

The code indicates a fuel mixture issue but doesn't indicate which direction. Before you cleared the codes you should have recorded the freeze frame data but that is gone until the code resets again. When it does, record the freeze frame data and post it here.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

New User

Jul 2, 2020, 2:38 AM

Post #3 of 6 (2225 views)
Re: 2003 Skoda Fabia P0170 Sign In

Thanks for the quick reply, you already helped me a little bit forward. When I saw freeze frame in my scanner I though it would be a freeze of the data at the moment you requested the freeze frame, I forgot to actually check this assumption. Here's the freeze frame of the current error code, I don't see anything weird but maybe any of you might:

Fuelsys1: CL
LOAD_PCT: 51.0%
ECT: 86deg C
SHRTFT1: 2.3%
LONGFT1: 2.3%
MAP: 68 kPa
RPM: 3521 /min
VSS: 105 km/h

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 2, 2020, 3:36 AM

Post #4 of 6 (2219 views)
Re: 2003 Skoda Fabia P0170 Sign In

You're right. That's not showing the problem. The code indicates a mixture problem but the adaptives do not.
The only thing that might be a little questionable is the MAP reading that seems a bit high for 51% throttle. The temp is also a little low but I don't know how long it had been running.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

New User

Jul 2, 2020, 8:51 AM

Post #5 of 6 (2197 views)
Re: 2003 Skoda Fabia P0170 Sign In

The freeze frame didn't register the throttle load (or at least my scanner doesn't show it for freeze frame). The 51% is the Load_PCT which as I understand it is more related to the airflow versus the maximum airflow. From what i've seen in the live data the Load_PCT is usually higher than my throttle position. (see also original post, 39.6% Load_pct & 19.6% TP(throttle position).

Regarding the coolant temperature being a little low, that is the opposite of what I would have expected. The error light came on after about 2 hours driving on the highway on a warm day. I know the ECT shows the correct ambient temperature before turning the car on and it's been around 85°C (and exactly in the middle of the dashboard gauge) since I started checking a few months ago.
However just to make absolutely sure, could this be a symptom or cause of the P0170 light and if so, how would I check?

Ps. I really appreciate the support

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 2, 2020, 8:59 AM

Post #6 of 6 (2190 views)
Re: 2003 Skoda Fabia P0170 Sign In

Again, I don't have any specs on this vehicle but I would have expected the operating temp to be higher.

Most vehicles these days run above 195F or 91C or higher.

You have a MAP sensor so you do not have anything measuring air flow. It determines load by reading vacuum through the MAP. It probably factors in TPS position also.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

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