Tackling rear lambda sensor

[hedges88]

My mum's little old Hyundai runabout has a DTC for open circuit on the rear lambda sensor heating element. As such it's running very rich so i want to not let her use it too much. If im correct it's found in the midsection part of the tail pipe. I have a lift, stands, chocks and I really decent old set of metal ramps.

I am capable of basic mechanics, have home level car tools but i see through research i need a special attachment tool for the job.

Given that I have the access that I need and basic tools, plus the ability to get the lamda probe tool socket, would this be a relatively simple job? I haven't done it before and I don't want to bite off more than I can chew. Is it a simple as it Looks?

Can anyone advise if it's simple enough for me to do or something worth paying a garage to do?

Grateful in advance for any good advice

[GreenV8S]

Research where it is on the car, look at pictures of the replacement part.

Get under the car and get your hand on the part you'd be replacing. How easy is it to get at? You willing to go through whatever contortions and discomfort are likely to be involved in replacing it?

If it's easy to replace, labour to do it is unlikely to be expensive. If it's expensive, that may be a clue it's not a job to take on lightly.

[hedges88]

GreenV8S said:

Research where it is on the car, look at pictures of the replacement part.

Get under the car and get your hand on the part you'd be replacing. How easy is it to get at? You willing to go through whatever contortions and discomfort are likely to be involved in replacing it?

If it's easy to replace, labour to do it is unlikely to be expensive. If it's expensive, that may be a clue it's not a job to take on lightly.

thank you for the advice. I never thought to use labour prices as a clue!

Research on the part and it's location have been done. The reason I said I thought it was located in the mid pipe was because i don't know the technical name for that section of the exhaust system. Certainly it is post three-way catalyst.

I kept thinking of only getting it up on the ramps when I was doing the job but it's not that hard really to do it just to check i guess

thank you for the help!

[tux850]

hedges88 said:

My mum's little old Hyundai runabout has a DTC for open circuit on the rear lambda sensor heating element. As such it's running very rich so i want to not let her use it too much.

If it is the downstream sensor are you sure it is the cause of rich running? I would expect it only to be monitoring the performance of the cat, with the upstream being responsible for closed loop control of fueling ratios.

[hedges88]

tux850 said:

If it is the downstream sensor are you sure it is the cause of rich running? I would expect it only to be monitoring the performance of the cat, with the upstream being responsible for closed loop control of fueling ratios.

I did monitor it and at full temperature it remains in open loop operation. I assume this is a default worst possible scenario fuel map it has decided to stick with due to a fault with the emission system.

The heating element error is bank 2 so that has made me believe it's postcat. Your post has intrigued my interest though because if the first cat is doing that then what is the tailpipe monitoring for?

[tux850]

hedges88 said:

I did monitor it and at full temperature it remains in open loop operation. I assume this is a default worst possible scenario fuel map it has decided to stick with due to a fault with the emission system.

That's a possibility. I wouldn't expect it though, but then lots of things happen that I don't expect so don't read too much into that!

hedges88 said:

The heating element error is bank 2 so that has made me believe it's postcat. Your post has intrigued my interest though because if the first cat is doing that then what is the tailpipe monitoring for?

Now I certainly wouldn't expect a Bank 2 in a 'little old Hyundai runabout'. What car/engine is it?

Edited by tux850 on Sunday 29th September 20:19

[E-bmw]

As has been said above post cat sensor is really just a check of cat efficiency in most cars.

Pre cat is the one that does all the work.

If it is running rich check the exhaust carefully for leaks as an air leak could be causing the mixture to be enrichened falsely.

If you do need to change an oxygen sensor make sure you use either NTK or Bosch as cheap ones just do not last.

[Super Sonic]

The reason you need the special tool is because the sensor has a wire coming out. If you are scrapping the sensor you can cut the wire and use a normal long socket or ring spanner to remove. Depending on access you may be able to use an oe spanner to replace.

[hedges88]

tux850 said:

Now I certainly wouldn't expect a Bank 2 in a 'little old Hyundai runabout'. What car/engine is it?

Edited by tux850 on Sunday 29th September 20:19

Apologies it's bank 1 sensor 2. I just mis spoke.

A Coupe V6 wedged into a getz would be a giggle!