high co emissions

thepriceofgaz

Active Member
Jan 6, 2018
7
0
hi all looking for help

leon cupra 2002

failed mot 2 months ago on high co

been to 3 garages so far with no help for any

only code i have on the car is for a short to ground on the n112 valve

first garage said it was the cat so i brought a new one took it back after fitting and the reading was the same

second garage had it a week had a little mess but didnt have a clue

third garage booked it in then they said to have a full diag done by a company called home tune in stafford at the cost of £72 he came out did the test and said to the garage that he couldnt find anything and narrowed it to the ecu

so sent the ecu away for testing came back with no faults

starting to really hate this car and that the garages by me are totally useless

any help much appreciated

ps

car runs and drives fine even the garage said so

i did try looking at the fuel trim both stay at 0

i read somewhere that if the n112 valve is faulty or not connected/resistor that it doesnt allow adaptive fueling hence the 0 fuel trim not 100% on that
 

Gaz20VT

Active Member
Aug 5, 2011
122
15
How high is high on the CO reading? Any issue with HC or Lambda?

A couple of things spring to mind that are worth checking.

You say you can look at the fuel trims - can you check the water temperature when the car has been driven for a while - does VCDS or your scan tool show ~90º? A dodgy temperature sensor can affect the mixture if it's failed and the engine defaults to Warm-up fuelling.

The other is the pre-cat lambda sensor itself.

Not sure on the N112 valve - if it's secondary injection or EGR-related it could well be related.
 

thepriceofgaz

Active Member
Jan 6, 2018
7
0
Thanks for the replays the readings were as follows

First fast idle 2.196
Second fast idle 1.209
Passed on natural idle
Also passed on lambda

Passed on hc
 
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thepriceofgaz

Active Member
Jan 6, 2018
7
0
Today I tested the n112 plug pin 1 and earth got 14 v so there's power there
Also swapped the n249 and n112 round and still only got a code for the n112 unplugged both got code for both
Also check the relay in engine bay with number 100 on it Ross tech say it's a possible cause I tested the relay by adding power and can hear it clicking so it is functioning
 
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Gaz20VT

Active Member
Aug 5, 2011
122
15
If you're consistently getting a code for the N112, and it's not the valve ('cos you've swapped them), then the fault could be with the wiring between pin 2 and the ECU. Any chance of checking continuity?

Checking the relay is clicking is not a guarantee that it's functioning properly. The High Tension contacts can still be poor even if the solenoid in the relay is clicking. Relay 100 seems to power lots of things so not sure it's that. However it could be good to replace it if it's cheap, just to eliminate it.
 

thepriceofgaz

Active Member
Jan 6, 2018
7
0
Yeah I can check pin 2 to ecu how would I do that lol I'm literally going by what I've read would I probe the ecu plug and pin 2 ?
 
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Gaz20VT

Active Member
Aug 5, 2011
122
15
Are you getting a code for N112 or N121 (EGR valve control)? How many pins on the connector?

In any case you need to figure out which pin in the ECU connector is supposed to be connected to the ECU pin of the valve.

Then with the ECU connector disconnected, (I probably don't need to tell you this but just in case - be very careful) put one probe of your multimeter onto the correct pin on the valve, and one probe onto the aforementioned pin on the ECU connector to see if you get continuity.
(For completeness, Continuity setting is the one where if you touch the probes together the multimeter beeps, and probably shows a few tenths of an Ohm resistance).

If you find you've got continuity (beep), try wiggling the bits of the wiring loom you can see, to understand if the connection is making/breaking due to a damaged wire.
 

thepriceofgaz

Active Member
Jan 6, 2018
7
0
the code is 17829 secondary air injection solenoid valve (n112)
p1421 -35-00-short to ground

there are two pins on the connector for the n112

from what ive found it should be ecu pin 105 from what i found so far
 

verbal_kint

Active Member
Apr 15, 2010
639
31
North West Kent
Thanks for the replays the readings were as follows

First fast idle 2.196
Second fast idle 1.209
Passed on natural idle
Also passed on lambda

Passed on hc

That is what the test centre will give as standard but tells you almost nothing, you need the values for each

CO, CO2 & O2 will be shown as % figures whilst the HC will be a PPM value.

You will need to go back to them and get the full readings.
 
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