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The ever returning engine warning light . fiesta zetec 1.25


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Guest bangerfan101
Posted

Swmbo'd daily little runner has a pain in the arse engine management warning light that keeps coming on

 

having pluged my cheapo ebay code reader in and turned it off on numerous occasions it keeps coming back as oxygen sensor faults

 

so far iv changed lamba sensor, , sparkplugs , egr , given it a good service with oil flushed out .

 

an its back .

 

 

now the next thing on the to do list im guessing at is the cat .

 

or do i just pull the bulb out ?

Posted

Isnt there an 02 sensor before and after the cat?

One of them two, or the cat?

Posted

The code should say which o2 it is, mine says bank 1 every few weeks, i just switch it off as it runs fine and has done for years.

Posted

Check the 3 vacuum/breather hoses linked by a T piece under the inlet manifold. They collapse giving an air leak and fault codes for lean fuel mixture.

Posted

Check the 3 vacuum/breather hoses linked by a T piece under the inlet manifold. They collapse giving an air leak and fault codes for lean fuel mixture.

 

I was just about to say the same thing. Was it a genuine/decent lambda sensor you fitted? I've never heard anything good about the cheap ones.

 

It will only be the CAT if you have a sensor after the CAT and the fault code is for this sensor, even then you can fool the ECU with a little voltage divider for the second sensor.

 

First sensor: used by ECU to run the engine in closed loop 

Second sensor: used to ECU to check CAT is working

  • Like 1
Posted

Must be a Ford thing, my eml was on on my Puma for the whole time I had it. Some sensor or other

 

Didn't make any difference whether it was on or I cleared it with my shit reader at the time she still ran fine*, and it came back on within 29 miles every time so I just left it on...

Posted

What is the actual code it brings up ?

Daverapid and rainagain are spot on about those breather pipes too

Posted

If its an 02-2008 type,wasnt there a throttlepot issue on these? Isnt there someone on here with access to the Tech bullitens on Fords?

Posted

error code will always be bank 1 as it's an inline four cylinder engine, sensor 1 will normally be pre cat, sensor 2 post cat. 

Posted

What is the actual code it brings up ?

Daverapid and rainagain are spot on about those breather pipes too

A friend at my last work bought his OH a polo and had something similar, the garage just changed the lambda probe twice and charged him for the privilege, he was moaning about the price they quoted him for changing the cat as that was their next move.  One lunch time I had a quick look at it with another colleague and we found part of the inlet was loose allowing an air leak and hence the lean mixture. That's the problem with fault codes a lot of garages just read the fault code and assume the sensor is wrong without looking at what the code is trying to tell them. 

Posted

Interesting stuff, might take the time to see what throws mine up.

Posted

The favourite fault codes to confuse garages are the fuel trim codes . You really need some live data on a diagnostic system to narrow down the fault . For example if the fuel trim is far too lean on idle but ok on the road then you have a manifold air leak of some description . If the trim gets worse under load then you could have a faulty maf sensor . So many people guess and throw parts at these faults

Posted

I really wanted that to be a link to a roll of black tape.

  • Like 3
Posted

I'm already well stocked on black duct tape ;-)

Guest bangerfan101
Posted

done both lamba's . will have a look at these pipes you speak of some time later .

 

the crate of brown ale im into is far more important this afternoon

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