Ford Focus LX - The Focus with the four Lambda Sensors - John Mitchell

The car is a 2006 (56) Ford Focus LX, with 113,000 on the clock.

The engine management warning light came on the other day. I took it to my local garage to have a look.

It turns out that all four Lambda sensors have gone. Yeah, before anyone says the Focus doesn't have four, I seem to have the only model that has two pre-Cat and two post. Obviously, replacing all four plus labour will cost about £800 (2/3 of what I paid for the car), though luckily, Euro Car Parts have a 57% sale on today, so that cuts the cost massively.

Has anyone else had the same trouble of all/both sensors going at the same time? Is it a common feature or can it be put down to something else?

I've not had the car for long and it's gutting to be honest.

Edited by John Mitchell on 30/04/2017 at 10:00

Ford Focus LX - The Focus with the four Lambda Sensors - Railroad.

That will be £800 wasted then. Now book it into a garage who knows what they're doing.

Ford Focus LX - The Focus with the four Lambda Sensors - John Mitchell

That's what I was thinking. I did wonder tbh. Would you care to elaborate as to what it might be?

Ford Focus LX - The Focus with the four Lambda Sensors - elekie&a/c doctor

Stand to be corrected,but I have never seen a basic model Focus of this age with 4 lambda sensors,and i can't find any technical info that shows an engine with 4.Perhaps your garage has an over optimistic guess-o-meter scanner.Take it to an indy garage that is able to read the info from the scanner and make an intelligent assesment of the problem.

Ford Focus LX - The Focus with the four Lambda Sensors - John Mitchell

It definitely has got four. Seriously, that conversation has been done to death now. The 56 LX is the only model ever with four (even Euro Car Parts has four part numbers – they were surprised as well). Ford also clarified it. My local garage is an indy.

Ford Focus LX - The Focus with the four Lambda Sensors - hardway

However many it has just saying they're shot is a bit of a guess.

And all four going at once?

Either it's just that the last one has gone south and the others went a while ago or I'd be confirming the fault.

Which I would do anyway.

So get some one who knows how to read live data and check the STFT and tha actual lambda out put.

Is it lean or rich,

And even then it would be on to the next step of the diagnosis.

Proper step by step procedure is the only way to avoid big bills.

Ford Focus LX - The Focus with the four Lambda Sensors - Railroad.

If it's got 4 lambda sensors then presumably it has two catalysts? I would do some fuel trim checks as the engine is most likely running too rich or too lean for whatever reason. The sensors are reporting the problem, and most likely not the cause of it.

Ford Focus LX - The Focus with the four Lambda Sensors - John Mitchell

It's actually just got the one Cat. Doesn't make a lot of sense why Ford did this.

I don't know much about the car's history… in that they could have all gone one-by-one, slowly with the light being turned off every so often.

I'm half tempted to get in touch with the previous owner.

Ford Focus LX - The Focus with the four Lambda Sensors - John Mitchell

All sorted.

Low voltage power supply to the O2 sensors was the problem – and yes, there are only TWO after all!! – but each sensor has two codes.

I spent £50 on a proper diagnostic at Halfords Autocentre in Ashford. They spent a couple of hours looking at the problem properly, unlike my local garage who tried charging me £800 after five minutes.

In the end, the only thing that needed doing was the coil (that was one of the causes of the light), HT leads and plugs.

Saving me over £500 on the original quote. Plus, I'm paying for it on their 0% credit over the next four months as it's just over £200.

Ford Focus LX - The Focus with the four Lambda Sensors - John Mitchell

Actually… all is not quite as it seems.

The light came back on again the other day so it's back into the garage for more work. :/

Ford Focus LX - The Focus with the four Lambda Sensors - jc2

Halfords will only have a diagnostic machine that is designed to work on all makes-it is better to go to a dealer of your make of car who should have a machine designed particularly for that make-whilst much of the electronics are similar they are not identical.

Ford Focus LX - The Focus with the four Lambda Sensors - Railroad.

The reason why the MIL lamp has taken a few days to come back on is because in that time the ECM has been going through a Drive Cycle with the EOBD Readiness Monitors set to Not Ready. During this period the ECM is not monitoring everything, and will not until a Drive Cycle has been completed. Anyone who connects a scantool during this period should see the status of the readiness monitors. ECM monitoring of the EOBD system will commence when the readiness monitors are set to OK or Ready. Your problem is not yet cured.

It also means that your problem is almost certainly something mechanical which is affecting combustion efficiency, which in turn is being picked up by the pre-catalyst O2 sensor B1S1. You need to do so some fuel trim checks to establish whether the engine is running too rich or too lean.

 

Ask Honest John

Value my car