Hi I had my MOT fail on emmisions, any advice what it is likely to be please, I feel so stressed it's only done 41 thousand miles, I have got a grand or so to fix it

Edited 19 November, 20232 yr by cheezemonkhai

What car have you got? Did they give you a copy of the emissions print out? Failing that, what's the exact failure described as on the fail sheet?

Edited 16 November, 20232 yr by StevesTruck

To the left shows a 2013 Citigo.

 

@lozza123Welcome.

I will flag your post for a mod to move it to the Citigo section.

(Maybe a change of title would be a good idea.)

44 minutes ago, StevesTruck said:

What car have you got? Did they give you a copy of the emissions print out? Failing that, what's the exact failure described as on the fail sheet?

The other thread of same title has a photo of the (thorough) fail sheet. Mrs Higgins - Forum How To - BRISKODA

 

Very, very rich at tailpipe, possible misfire?

It's a Skoda citigo could this be a lambda sensor

@lozza123When were the spark plugs replaced and the Air Filter looked at to wee if clean / fresh, or replaced?

Spark plugs and air filter changed it's not that

it can be a leak in the exhaust .

2 hours ago, mrcreosoate said:

it can be a leak in the exhaust .

I thought your issue was not having a leak in your exhaust so that the waffer thin mint caused excess back pressure?

Hi there, similar emissions as in original post caused mot failure. Plugs, filters 1 year old, 40k miles citigo 2015. Drives, starts like new, no faults logged, no warning lamps on the dash, no smoke from exhaust, no holes in the exhaust system....

I see there was no resolution posted. Appreciate throwing ideas what could be causing the high results on emissions

15 hours ago, beskid said:

Hi there, similar emissions as in original post caused mot failure. Plugs, filters 1 year old, 40k miles citigo 2015. Drives, starts like new, no faults logged, no warning lamps on the dash, no smoke from exhaust, no holes in the exhaust system....

I see there was no resolution posted. Appreciate throwing ideas what could be causing the high results on emissions

it goes too rich, too much gasoline, low air.

lambda sensor is correcting amount of fuel.

it have to get some issue on scan tools.

those values are like you dont have catalisateur and O2 sensor.

Hi, attached the emissions report and screen grab from car scanner app,

based on the code P0053 I have ordered precat lambda. No idea why the P004 pops up as the car is not fitted with turbo. (60ps model...). Vvt actuator seems to be working and not seized. As precaution I checked pvc, map and inspected throttle body and all these seem ok. Will advise once new lambda fited later in the week

delete those errors and rescan again complete scan.

excluse turbo options scan (non automatic)

before replacing lambda, check wires, connestors, often issue... measure resistance on lambda wires

this is copied from Google AI.

Resistance:

To test lambda sensor resistance, disconnect its electrical connector, set a multimeter to the Ohms (Ω) setting, and measure the resistance across the two heater wires, which should typically be between 2 and 14 ohms at ambient temperature but can be higher when the sensor is warm. A reading of zero (open circuit) or very low resistance indicates a failed heater element, suggesting the lambda sensor needs to be replaced. 

Voltage:

Step-by-Step Guide

1. 1. Allow the Engine to Warm Up:

   Start your Citigo's engine and let it reach its normal operating temperature. 

2. 2. Set the Multimeter:

   Turn your multimeter to the DC voltage setting. A measuring range of 1V or 2V is suitable. 

3. 3. Identify the Signal Wire:

   Find the lambda sensor's signal wire. This is typically the "black" wire, but it's crucial to consult your Citigo's circuit diagram to identify the correct wire. 

4. 4. Connect the Multimeter Probes:

   Insert a back-probe test lead into the sensor's connector to contact the signal wire. Touch the red probe of the multimeter to the signal wire. Touch the black probe to a good ground point on the vehicle, such as the chassis or battery negative terminal. 

5. 5. Observe the Voltage Reading:

   With the engine running at a steady speed (around 2,500 rpm), observe the multimeter. 

   • Good Sensor: A functional lambda sensor will show a rapidly fluctuating voltage, cycling between approximately 0.1V and 0.9V. 

   • Faulty Sensor: If the voltage remains steady at a fixed value, or if it doesn't change, the sensor is likely faulty and needs to be replaced. 

Important Considerations

• Heated Lambda Sensors:

  Modern lambda sensors are heated. You can also test the heater element's resistance with the multimeter set to the ohms (Ω) function. Consult your vehicle's service manual to identify the heater wires (usually two of the same color, like white) and their specifications. 

• Refer to Your Vehicle's Manual:

  Always refer to your vehicle's specific service manual to confirm the correct wire colors, specifications, and test procedures for the lambda sensor.  "

Edited 25 August, 202525 Aug by imart143

Hi there,

Although no obvious corncerns have been identified I did as follows:

1. Upon inspection the PVC valve located on top of engine allowed some air to pass in both directions(when blowed into the hose) £14 new valve

2. Engine oil level was approx 0.5l above top of dipstick max notch, (believe oil could splash by contact with piston causing higher hc emissions ) 1 l of oil has been drained to be on safe side, now dipstick shows half level

3. Some cataclean added to 1/4 tank

4. Precat oxygen sensor replaced to be on safe side, £25 for non original

5. As the car doesnt come with engine temp gauge I wasnt sure the tester performed the test on warm engine...prior to retest I drove the car for few miles on low gears to ensure everything is warm

As a result the emissions have passed with perfect results as shown, hope that helps anyone in same situation

i heard that oil level can harm but never see it.

good is to replace PCV valve.

probably lambda was faulty..