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Is it likely to be an 02 sensor?


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Looks like I'm still chasing this.¬†ūüėí

Engine light has come on again after about 100 miles, only this time I've got a different code (progress I guess!).

1 Fault Found:
16556 -  Fuel Trim; Bank 1: System Too Rich
        P0172 - 35-00 -   -
---------------------------------------------------------------------------

I haven't looked at fuel trims yet, as engine is cold so will take it for a drive later to see what it's doing. But is there something I'm missing on the vacuum/air side to check for leaks? A system that kicks in later when hot and driving, egr or breather system or something like that? as the trims looked pretty normal initially.

 

Edited by RvB
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Well that's a long list of possibles to keep you busy: http://wiki.ross-tech.com/wiki/index.php/16556/P0172/000370 

if the vacuum hoses look old and are long enough cut the ends off and reseat them. Brake servo hose is a common fail as it gets brittle. Hot problem could be EGR, manifold leak, fuel side, compression, all sorts of stuff, just work your way thru the cheap and free stuff methodically.

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On 1/22/2019 at 10:59 AM, RvB said:

My lad's 2003 Arosa 1.4 Sport brought the engine management light on a couple of days ago. Car was running fine before it came on and after too. I've put vag com on it and got this:

1 Fault Found:
16804 -  Catalyst System; Bank 1: Efficiency Below Threshold
        P0420 - 35-00 -  

 

I've cleared the code and driven it about 10 miles and the eml hasn't come back on yet. I've checked for exhaust leaks and can't see/hear anything, so I'm wondering if the knowledgeable folk of clublupo have come across this one before. Do the o2 sensors fail with age on these cars or is it more likely the cat itself?

We got the car in November and it hasn't done a lot of miles since as he's still learning to drive, in fact it hasn't done a lot of miles in the last few years as the previous owner only did about 1200 miles a year and so did the previous owner to that. So I'm hoping it's just gunged up and a few good spirited drives will clear it out a bit, but if not any ideas where to look?

Give it a full dose of cat cleaner and give it half-to an hour on a motorway

Edited by weslangdon
you have had the same advice already, sorry
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15 hours ago, LR5V said:

Could this be Green sensor?

The coolant temp sensor you mean? Looks like it was replaced last year by previous owner, temp gauge and vcds shows 90 when up to temp.

 

13 hours ago, mk2 said:

My hunch is an air/vacuum leak.

I'm thinking that too, but where is the thing. I've been through the vacuum lines and can't see anything. What about the evap thing, when does that kick in? Anywhere in the egr system that would allow a vac leak when it kicks in? Is that a non return valve on the dangly pipe coming from the egr valve?

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Yeah if VCDS report both temp sensors correct at running, then I'd say the sensor is ok.

my guess is what is happening is that the ecu is struggling to keep the idle within limits. If air is getting in, it has to pull fuel to bring the rpms down. But then the O2 will pick up a lean mix exhaust- not good- then try and shut down the throttle body. But the blow by gasses (low in oxygen) will make up too much of the air portion and it'll go rich again. So the ECU will be really working to keep everything on the money. Then it'll just quit. Light on.....

had an idea... when hot, what is TPS doing? Should be about 2% ish.

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Right, so car is hot, just been driven 25 miles. Fuel Trims look perfect!

20190321-04.PNG.bee0889a49749c5e0e9fc9f7092c2cfa.PNG

20190321-03.PNG.32c654ac68e480774a3abe6d5ee9639a.PNG

Throttle Position blocks

20190321-02.PNG.41cd0fe852c16cf35237da79b1ccf808.PNG

Interestingly the eml was on when I setup vcds, so went into fault codes and got this.

1 Fault Found:
17582 -  Fuel Trim; Bank 1: Injection Timing Deviation (Balance Fault)
        P1174 - 35-00 -   -
---------------------------------------------------------------------------

I didn't clear the code and went and did the above tests, then went back into fault codes to clear it and had it gone and been replaced with the running rich one.

1 Fault Found:
16556 -  Fuel Trim; Bank 1: System Too Rich
        P0172 - 35-00 -   -
---------------------------------------------------------------------------
 

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Those numbers are off. The one that gets me is the load. 12% what?! And the accelerator pedal at 15% huh? Was your foot on the pedal during the measurements? At idle, it should be 0. The car is a manual (not auto box?).

The label file is the right one isn't it? Its just that the numbers don't make sense to me.

just had an idea... is there normal power when you give it some stick while driving? Like at highish revs 3k+? Just wondering if there's a fuel supply problem.

Edited by mk2
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14 minutes ago, mk2 said:

Those numbers are off. The one that gets me is the load. 12% what?! And the accelerator pedal at 15% huh? Was your foot on the pedal during the measurements? At idle, it should be 0. The car is a manual (not auto box?).

The label file is the right one isn't it? Its just that the numbers don't make sense to me.

Reckon it's the right label file. Engine control Module has part number 036 906 034 BA, matches label file 036-906-034-APE.lbl which is for AUB engines if I open that file up.

Definitely no foot on the pedal, I was in the passenger seat! And yes manual, not auto.

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I have no idea whats going on...

Take some measurements with hot engine, not running. Test pedal. 0-100% ; TPS should follow (in theory).

 

Edited by mk2
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16 hours ago, mk2 said:

just had an idea... is there normal power when you give it some stick while driving? Like at highish revs 3k+? Just wondering if there's a fuel supply problem.

Yep, get it above 3K and it sings, pulls well and revs sweetly up to the red line.

 

6 hours ago, mk2 said:

I have no idea whats going on...

Take some measurements with hot engine, not running. Test pedal. 0-100% ; TPS should follow (in theory).

 

Pedal at rest = 14.5% moves through the range until the stop = 85% and back again to 14.5% at rest.

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Ok, so no fuelling problem. Good. So engine is fine.

I'd say it's almost dead cert something that only happens at idle. So that narrows it down to air leak, dirty/iffy sensor(s), or maybe throttle body(TPS) or pedal. Hmm.

Anyone else on here know what the pedal in a 1.4 sport should read? I know on my lupo it goes from 0-100%. I'd guess the same...?

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