Failed MOT - again on emissions

V

Verbdog

A2OC Donor
Last year the engine light came on and a mobile mechanic diagnosed the rear lambda sensor needed replacing so it was. He cleared the fault light but after a few days it came back on, he said the front sensor had now gone wrong and this often happened when one is replaced. I struggled to believe that and kept meaning to post on her for advice but never got round to it. I got the A2 for the wife and she uses it so little other things took priority.

However it's now failed the MOT on:

1. Exhaust emissions carbon monoxide content at idle excessive [7.3.D.2c]
2. Exhaust emissions carbon monoxide content after 2nd fast idle excessive [7.3.D.2b]
3. Exhaust emissions Lambda reading after 2nd fast idle outside limits [7.3.D.2b]

After searching here the remedy appeared to be replacing the front Lambda, which I did. The EM light cleared so I thought I'd solved the problem and took it in for another test.

Sadly it failed again on the first 2 points, so replacing the Lambda only solved point 3 from the first test.

The inspector said it might just need redex and a decent drive to clear the exhaust (which would fit with the car only having done very short journeys for the last 2-3 months).

On the way back home the Engine light came back on...grrrr

A local garage hooked it up and reported:

17559 No script 7566 sender for inlet manifold pressure g71 implausible
17584 Bank 1 lambda connection Rear Cat control limit reached.


Anyone want to offer some informed advice to point me in what now needs to be done?

Forgot to mention that it's a 1.4 2001 petrol
 
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Hi mate

Here is a full break down on what those 3 fault codes mean:

17566/P1158 - Manifold Pressure Sensor (G71): Implausible Signal

Possible Causes:

* Connections to / from sensor (G71) faulty
* Sensor (G71) faulty

Possible Solutions:

* Check wiring and connections
* Check hoses
* Check / Replace Manifold Pressure Sensor (G71)

17559/P1151/004433 - Long Term Fuel Trim Additive Air; Bank 1; Range 1: System too Lean

Possible Symptoms:

* Malfunction Indicator Lamp (MIL) active

Possible Causes:

* Intake System faulty/leaking
* Fuel Pressure, Fuel Pressure Regulator and Fuel Pump faulty
* Fuel Injectors faulty/leaking
* Exhaust System faulty/leaking
* Activated-Charcoal Filter/System faulty/leaking
* Secondary Air Injection System faulty/leaking
* Lambda/Oxygen Sensor(s) before Catalytic Converter faulty
* Lambda/Oxygen Sensor(s) after Catalytic Converter faulty

Possible Solutions:

* Check Intake System for Leaks
* Check Fuel Pressure, Fuel Pressure Regulator and Fuel Pump
* Check Fuel Injectors
* Check Exhaust System for Leaks
* Check Activated-Charcoal Filter/System
* Check Secondary Air Injection System
* Check Lambda/Oxygen Sensor(s) before Catalytic Converter
* Check Lambda/Oxygen Sensor(s) after Catalytic Converter

17584/P1176/004470 - Bank1: O2 (Lambda) Correction Behind Catalyst: Control Limit Reached

Possible Causes:

* Intake Air System leaking
* Oxygen Sensor(s) and/or Oxygen Sensor Control faulty

Possible Solutions:

* Check Intake Air System for Leaks (False Air)
* Check Oxygen Sensor(s) and/or Oxygen Sensor Control (all of them!)


So a common fault listed in those codes would be a leaking air intake system.

John
 
Yer you can do that as well.

But I would deffo check for air leaks etc and check through on the possibilities listed in previous post under each fault.

John
 
Ok, so I checked the rubber hoses and although no obvious holes I cleaned and taped up both pipes wherever they had signs of rubbing (the top pipe has quite a lot where it runs behind that plastic manifold on top).

Cleared the codes and took it for a nice run down the A2 (A2's on the A2 how cool :D ), after 18 miles the engine light came back on and I'm just glad my daughter wasn't there with the expletives streaming out!

Fault codes now read:

17584 P1176 - control limit reached on rear O2

16524 - O2 sensor circuit, B1 S2, No activity detected.

Would this be a wiring issue to that sensor? It was replaced only about 9 months ago and less than 800 miles. I'm hoping that the guy that fitted it used a direct fit rather than jury a compatible.
 
I'd say that rear O2 sensor is suspect. Either it's the wrong part, or it's a faulty part, or the wiring is damaged, or he never actually replaced it in the first place, just cleared your codes.
 
I have tried to test the Control Module for the sensor and the values returned were 0% and 0%, the advice available is that if both are pos or neg then it's likely a sensor fault, if one is neg and the other pos then look to a faulty MAF.

So my zeroes don't help :)
 
Mine failed its MOT in oct, due to high emmision levels.

The agrage took it out for two 'hard drives' to clear the emmisions, and eventually it worked. Likewise, I had to replace a Lamba sensor the previous year.
 
I had a Mazda MX5 that failed on Emissions. The MOT Tester said it would be one of two things Lamba sensor or Catalytic Converter. It was going to be very expensive to replace both. So the cheaper option was the Catalytic Converter. So I replaced this part first and fortunately that was the problem!

As you have already replaced the sensor I would now look at you CAT. They only have a limited life span!

Darren
 
Phil makes a good point though. It's always worth giving the car a real workout before going for the emissions test it does make a big difference.

Hope you get yours fixed.
 
Jacked the car up and did a visual check on the rear O2, found that the "Mechanic" who did the replacement last year used a compatible one and cut the old connector off, and joined with crimp ons instead, 2 of these wires were free so that would cause problems! Annoyed that he never even bothered to ask if we'd prefer to keep a direct fit/original, but then to not make sure the connections were solid is just taking the proverbial.

2 hours later and with a sore back from trying to work under the car all looks good, went for another 20 mile blast and no light came back on. Result!

Did another blast to the MOT place as last day for retest and sadly he stopped when the first test failed, the Fast idle CO2 was fluctuating between .7 and .9 - last time it was at .5

The tester said it could be the Cat.

Needless to say I'm not happy.

Can vag-com do any tests on the Cat?

Edit: I think with all the focus on the Engine Light being on I've missed the EPC light being on but Vag-Com shows no errors?
 
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hi glad you sorted the lambda probe---why don't some garages do a proper job? a good mechanic you trust is hard to find(luckily i have a great independent) your epc light may just be an iffy brake light switch,reverse up to a wall and repeatedly apply the brakes and see if it works all the time.
hope you get a ticket soon cheers mike
 
I thought I had a decent independent but slowly lost trust in him, it vanished altogether when the engine mount broke in my Leon in December, he stated categorically that the only solution was a new engine at £1600 minimum.

Coming from an engineering family I knew that most metals can be joined (all it needed was a new flange welded and tapped on the engine casing for the topmost bolt to secure into. The engineering firm charged £200 for their work, and another garage I've started to use (Auto22 - nice little charity outfit) charged £350 for taking the engine out and in. I saved a grand by not being taken for an easy ride.

I'll try that brake test after the Rugby :) , thanks for the advice.
 
And it passed at Kwik-fit this afternoon.

Which part or a combination of new plugs/air/oil or Lambda sensor or Italian tune-up worked I can't say, but I'm a happy chappy.
 
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