Hi All,

My engine management light came on and gives an error code for the lambda sensor. I've never replaced one before, though it looks pretty straightforward online - the one question I have is what type to replace it with.

Ebay lists lambda sensors for a Mk1 ford focus starting at £15.

The guides I've seen tell me that you must replace the sensor with the same type that you removed; else the onboard computer will hate you and cause trouble.

Looking at a ford parts website the sensors sell for well over £100.

Anyone with any advice on which type of sensor to replace my current one with?

On that note - anyone with advice on how to tell what make my current sensor is?

Cheers,

Dr

Ok. First you need to tell us the code fully. You mush have been told bank 1 sensor 1 or something like that. Once you know which sensor it is, it should have a coloured connector. Green or blue. You need to replace the sensor for the same colour. And make sure you get oem quality or original Ford. Replacing the sensor is easy make sure the vehicle is cold and not started. You might choose to use wd 40 if the sensor Is stuck. Using a spanner or the special tool remove the old and replace with new. Use copper grease as well on the treads but don't touch the sensor tip.

Don't buy a cheap one is my only advice..

Yh. Very good advice. Cheap is not better.

Thanks chaps, that's really great to get this info so quickly.

As it happens, I've gotten an OBD2 scanner and can tell you the code: P0420

On an aside, I've got the option of a few ford focus models when I connect the scanner; none of them is the petrol 1.8 zetec. Anyone with advice on the most suitable option to choose instead?

• Focus 1.6i
• Focus VCT 1.6i
• Focus CMAX VCT 1.6i
• Focus CMAX 1.6i
• Focus Ghia 1.6i

Anyway, the 0420 code seems to mean that my CAT efficiency has decreased. I'm therefore not convinced that changing the O2 sensor would help. Options for me seem to be to either clean the CAT or to replace it. I think I'll go for the cleaning option first, then the replacement if nothing helps.

I understand that the CAT doesn't normally fail, and even though my car is now 12 years old it's only done 74k miles. I think that there may be an upstream problem. A week ago my car didn't start first time after I'd made a short trip and left the car for a few mins... It started fine on second attempt. This happened a couple of times in the same day. I thought perhaps the sparkplugs had fouled or the fuel pump had a problem. The problem with the CAT makes me think that it's occurred secondary to the sparkplugs.

Any ideas?

My plan is to take it to the garage on Monday to get a checkup; then I'll have a better idea of the location of the problem. If there's anyone that'd spotted the heart of the issue from what I've said, I'd be grateful of your advice.

Cheers,

Dr

For a car that is low mileage and 12 years old says it's not been driven often and so I would suggest a tune up.

A p0420 code doesn't strictly mean your cat is at fault..

Did you manage to solve the problem?

UP!

I captured a live data of oxygen sensor and can't understand what is bank1, bank2 and sensor1, sensor2. Video please finde here: 

 

Are bought sensors working? I will wait yours comments.