Hi all,

Had a 2012 Titanium Auto for the last 4/5 years. It was my first car, and I usually drive my partners now and she drives the ford so forgive my ignorance and lack of knowledge!

At it's recent MOT a front coil spring had collapsed and it had also failed the emissions test under the lambda test.

A family friend is happy to carry out the work and has just asked me to order the springs, some catacleaner and a lambda sensor.

The car was previously modified when I got it (lowered) however it was raised again a few years ago. 

For coil springs I'm guessing either of these would do the job?  https://www.autodoc.co.uk/kraft/18524143 or https://www.eurocarparts.com/p/starline-coil-spring-627592889 ?

The confusing bit for me is the lamda sensor. Would I require a pre cat sensor or post? or both? I've been looking at these but no idea if they'd be suitable... https://www.autodoc.co.uk/denso/1665554 & https://www.eurocarparts.com/p/denso-lambda-sensor-710591245

Thanks in advance!

Failing the lambda test doesn't necessarily mean a lambda sensor is faulty.  It just means the amount of oxygen in the exhaust is wrong.  We'd need to know which side of Lambda 1 the actual figure is to determine whether it's overfuelling or underfuelling before deciding which parts may be needed for the repair.

If you do just want to throw a lambda sensor at it, then start with the pre-cat sensor.  That's the one that controls fuelling.  The post cat sensor just checks how well the the cat is working.

Must admit I've only ever had poor results with cheap suspension springs.  If you're intending to keep the car, I'd probably go for a midrange brand instead of the Starline linked there.

16 minutes ago, TomsFocus said:

Failing the lambda test doesn't necessarily mean a lambda sensor is faulty.  It just means the amount of oxygen in the exhaust is wrong.  We'd need to know which side of Lambda 1 the actual figure is to determine whether it's overfuelling or underfuelling before deciding which parts may be needed for the repair.

If you do just want to throw a lambda sensor at it, then start with the pre-cat sensor.  That's the one that controls fuelling.  The post cat sensor just checks how well the the cat is working.

Must admit I've only ever had poor results with cheap suspension springs.  If you're intending to keep the car, I'd probably go for a midrange brand instead of the Starline linked there.

Hi @TomsFocus thanks for the speedy reply. Good to know about the difference in the pre and post cat sensors and their function.

For the emissions:
Fast idle test Lambda -  1.118 for a range of 0.970 and 1.030

Second Fast Idle Lambda - 1.112 for a range of 0.970 and 1.030.

We are actually looking at selling the vehicle hopefully within the next 3 months as we now don't require a second car!

21 minutes ago, Dom23 said:

Hi @TomsFocus thanks for the speedy reply. Good to know about the difference in the pre and post cat sensors and their function.

For the emissions:
Fast idle test Lambda -  1.118 for a range of 0.970 and 1.030

Second Fast Idle Lambda - 1.112 for a range of 0.970 and 1.030.

We are actually looking at selling the vehicle hopefully within the next 3 months as we now don't require a second car!

Lambda figure of 1.1 is very lean.  There's more oxygen in the exhaust than there should be.  This is often caused by a hole in the exhaust, sucking in fresh air from outside to combine with exhaust gasses, which gives a false reading by the time it reaches the tailpipe.

Ideally, the next step would be to check the actual lambda sensor readings using live data on an OBD2 diagnostic.  If the readings are wrong, that means there's a leak before the lambda, or even around the intake manifold.  If the lambda sensor readings are good, that suggests an exhaust leak somewhere after the sensor.

30 minutes ago, TomsFocus said:

Lambda figure of 1.1 is very lean.  There's more oxygen in the exhaust than there should be.  This is often caused by a hole in the exhaust, sucking in fresh air from outside to combine with exhaust gasses, which gives a false reading by the time it reaches the tailpipe.

Ideally, the next step would be to check the actual lambda sensor readings using live data on an OBD2 diagnostic.  If the readings are wrong, that means there's a leak before the lambda, or even around the intake manifold.  If the lambda sensor readings are good, that suggests an exhaust leak somewhere after the sensor.

Thanks. That's a good point. The garage did mention they suspected there was a minor leak in the exhaust which I completely forgot, therefore guessing that a new sensor is potentially a waste of time and money.

53 minutes ago, Dom23 said:

Thanks. That's a good point. The garage did mention they suspected there was a minor leak in the exhaust which I completely forgot, therefore guessing that a new sensor is potentially a waste of time and money.

Yep.  I wouldn't bother with the Cataclean either personally.

28 minutes ago, TomsFocus said:

Yep.  I wouldn't bother with the Cataclean either personally.

Yeah, I'll see if we can sort the exhaust and hopefully that will solve it.

Out of interest from my various tabs, I note for the pre-cat lambda's some list them as being for manual, the odd one for automatic transmission and others with none listed. Are they really that specific, or simply just inconsistent labeling on the websites?

7 minutes ago, Dom23 said:

Yeah, I'll see if we can sort the exhaust and hopefully that will solve it.

Out of interest from my various tabs, I note for the pre-cat lambda's some list them as being for manual, the odd one for automatic transmission and others with none listed. Are they really that specific, or simply just inconsistent labeling on the websites?

They can be that specific.  There are a few different cat & lambda setups for the Mk7 Fiesta.

If you can confirm your engine size and whether it's pre or post Mk7 facelift then we can check which lambda should be correct.

52 minutes ago, TomsFocus said:

They can be that specific.  There are a few different cat & lambda setups for the Mk7 Fiesta.

If you can confirm your engine size and whether it's pre or post Mk7 facelift then we can check which lambda should be correct.

1.388 cc
In terms of pre or post, I'm not entirely sure... would this photo help from when it was purchased back in 2019? 😆 (no. plate is only blurred as I've managed to find this screenshot this from an old post on this forum when I'd done it then)

That is pre-facelift.

 

These are the genuine Ford parts numbers.  They can be cross referenced with any aftermarket parts.

Pre-cat - 1800955

Post cat - 1743702

https://www.ebay.co.uk/itm/393390028970?

https://www.ebay.co.uk/itm/393390029697?