Technical Siezed O2 Sensor

[ReadySteady98]

Hi guys I have a 15 year old Fiat Panda and ever since I got it I always knew that the O2 sensors need replacing. I ordered a new sensor on eBay because it was coming up on the OBD reader that one out of the 2 is faulty. I opened the bonnet up to see that the one closest to the ground had a broken cap. The O2 sensor bolt that goes into the manifold looks rusted but it’s solid. Anyways I got a spanner and used the rounded side for maximum grip and the thing wouldn’t even budge. I then went to Halfords and got myself some wd-40 penetrant oil spray and put than on for an hour and tried again still wouldn’t move a single bit. I then went for a drive made sure that the exhaust got warm (not too warm) and applied the penetrant oil again and this time left it over night. Woke up this morning thinking that it would solve the issue and again the thing just wouldn’t even budge.

Neve knew it would be that difficult, I am now scared of damaging the manifold and having to get it replaced. Has anyone on here ever got an old o2 sensor out that’s been there for 10 years + successfully?


Also if I just don’t replace it, will I have issues with my car. The car itself drives fine and I don’t notice any lose of power. Just completely normal.


What do you guys recommend I do?

Thank you

 

[koalar]

If heating the exhaust up running the engine doesn’t work

I would use a blow torch and heat the outside boss to cherry red.

If you already have a replacement you can brake the top off and use a socket and breaker bar

Penetrating oil will not do any thing the two parts are fused together and there’s no place for the oil to get in

Only when the initial bond has been broken will penetrating oil work

 

[ReadySteady98]

If heating the exhaust up running the engine doesn’t work

I would use a blow torch and heat the outside boss to cherry red.

If you already have a replacement you can brake the top off and use a socket and breaker bar

Penetrating oil will not do any thing the two parts are fused together and there’s no place for the oil to get in

Only when the initial bond has been broken will penetrating oil work

I’m thinking of leaving it but some mechanics are saying it won’t pass an MOT test. What’s the worst that can happen if I just leave it as it is for let’s say 7 months which is when my next MOT is due?

 

[koalar]

Post CAT not so much as far as I know (yours)

Pre CAT can cause a lot of damage depending


If it’s was pre CAT you could disconnect it so the car runs on default values

These are safe and slightly rich.

However the extra fuel wasted you might as well payed someone to change it. Plus nicer for the rest of use in less emissions. (Not yours as it’s post CAT)

If your near Crewe I will take it out for you

 

[Goudrons]

You need the right tool.
A proper O2 sensor socket and a socket driver like a ratchet (you could extend with a bit of pipe) or breaker bar.

There are two slightly different types of O2 sockets.
I find this style better,

Hilka Pro-Craft Oxygen Sensor Wrench - Screwfix

Order online at Screwfix.com. For quick removal or replacement of Oxygen Sensors. Offset drive with wire gate accesses sensor from the side, preventing damage to wire harnesses. Suitable for heated and unheated oxygen sensors. Star shaped socket for accessibility fits standard wrench. FREE next...

www.screwfix.com

I used to use one of these types but found they do tend to slip and muller the nut.

Laser 2120 Oxygen Sensor Socket 3/8"D 22mm | Euro Car Parts

Laser 2120 Oxygen Sensor Socket 3/8"D 22mm at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

 

[ReadySteady98]

You need the right tool.
A proper O2 sensor socket and a socket driver like a ratchet (you could extend with a bit of pipe) or breaker bar.

There are two slightly different types of O2 sockets.
I find this style better,

Hilka Pro-Craft Oxygen Sensor Wrench - Screwfix

Order online at Screwfix.com. For quick removal or replacement of Oxygen Sensors. Offset drive with wire gate accesses sensor from the side, preventing damage to wire harnesses. Suitable for heated and unheated oxygen sensors. Star shaped socket for accessibility fits standard wrench. FREE next...

www.screwfix.com

I used to use one of these types but found they do tend to slip and muller the nut.

Laser 2120 Oxygen Sensor Socket 3/8"D 22mm | Euro Car Parts

Laser 2120 Oxygen Sensor Socket 3/8"D 22mm at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

Would this not damage the exhaust. I used the hex side and tied with with a strong rope and pulled and nothing happened. This was when it was really warm too. I phoned a local mechanic and he claims to have “tools to get it done properly” but it would cost £40. And if it goes wrong then I need a new cat. It’s a bit of a gamble tbh.

 

[Pugglt Auld Jock]

You need the right tool.
A proper O2 sensor socket and a socket driver like a ratchet (you could extend with a bit of pipe) or breaker bar.

There are two slightly different types of O2 sockets.
I find this style better,

Hilka Pro-Craft Oxygen Sensor Wrench - Screwfix

Order online at Screwfix.com. For quick removal or replacement of Oxygen Sensors. Offset drive with wire gate accesses sensor from the side, preventing damage to wire harnesses. Suitable for heated and unheated oxygen sensors. Star shaped socket for accessibility fits standard wrench. FREE next...

www.screwfix.com

I used to use one of these types but found they do tend to slip and muller the nut.

Laser 2120 Oxygen Sensor Socket 3/8"D 22mm | Euro Car Parts

Laser 2120 Oxygen Sensor Socket 3/8"D 22mm at the lowest UK prices from Euro Car Parts UK’s No.1 for Car Accessories, Car Styling & Car Care. Buy today Online, In store or by Phone + Branches Nationwide – Next Day UK Free Delivery.

www.eurocarparts.com

Trouble with "proper" sensor sockets is they are all split down one side. Of course they have to be to allow for the wires. But because of this they tend to open up when you really lean on them. I have that kit of two linked to in the above post and they do work well. Mostly when a sensor is so rusted in place that you can't move it with the specialist socket they are needing renewed anyway so just cut the wires off and use a normal deep socket. If that doesn't seem to be doing the trick then it's time to get the blowtorch out as Koalar says. Watch how much force you apply though, I once partially ripped the threaded slug out of the pipe on our old Panda! To be fair the pipe was quite rusted and really needed replaced anyway

 

[Pugglt Auld Jock]

PS to the above. If heat is required it's much more easily applied with an oxy-acetylene torch. Might be worth asking your local wee garage what they might charge to tackle this for you, might be less than you think?

 

[chris3234]

Ideally you could do with a garage with an induction heater to fit around teh fitting on the pipe but not many with one if these

 

[Pugglt Auld Jock]

Ideally you could do with a garage with an induction heater to fit around teh fitting on the pipe but not many with one if these

Ooooh, an induction heater! yes. Absolutely ideal candidate I'd have thought.

 

[ReadySteady98]

Which one is the pre cat sensor is that the one nearest to the ground at the bottom? Or the one above it? Both need replaced?

 

[koalar]

Would this not damage the exhaust. I used the hex side and tied with with a strong rope and pulled and nothing happened. This was when it was really warm too. I phoned a local mechanic and he claims to have “tools to get it done properly” but it would cost £40. And if it goes wrong then I need a new cat. It’s a bit of a gamble tbh.

Needs to be hot like this



You can use a propane torch also

It’s the only way without risking rounding the head if they are very very tight

I only ever use a 22mm ring

When they been in for 15-20 years they are nearly all impossible to undo safely without heat

Occasionally you get lucky if it’s either been replaced before and anti seize used

 

[koalar]

Which one is the pre cat sensor is that the one nearest to the ground at the bottom? Or the one above it? Both need replaced?

Pre CAT top

Only damage one need replacing

Or relating to a error code

 

[koalar]

I phoned a local mechanic and he claims to have “tools to get it done properly” but it would cost £40. And if it goes wrong then I need a new cat. It’s a bit of a gamble tbh.

Total Micky take

5 minutes

No risk,

Something a garage is doing week in week out

And tyre and exhaust places to

 

[ReadySteady98]

Total Micky take

5 minutes

No risk,

Something a garage is doing week in week out

And tyre and exhaust places to

It is mate I agree, another garage was like £69 an hour for each seized bolt. Like what the hell!?

 

[ReadySteady98]

Wish I watched this video before rounding it off. It still has some edges and the spanner could still get a good grip on it, might get a blow torch from b&q tomorrow and give this a last try. He states in the video that this is apparently 20 years old sensor!!!

 

[koalar]

Wish I watched this video before rounding it off. It still has some edges and the spanner could still get a good grip on it, might get a blow torch from b&q tomorrow and give this a last try. He states in the video that this is apparently 20 years old sensor!!!

If it’s very stuck it needs to be much more heat as per post 2 And shown in video post 12

It will take a fair bit longer to heat up as propane isn’t as hot

Aim the torch at the boss heat rises so aim mostly at the lowest point
I couldn’t find a decent video with an o2 sensor.

Internet is swamped with people making video. Unfortunately there not all correct

Not easy if it’s windy
Use the hottest part of the flame

 

[ReadySteady98]

Ok I will do that. I have found this on b&q’s website it’s just a wee one enough for a small job. It heats up to 1350. Apparently you just need to heat it up to 600 to get it moving, so it should be sufficient I think.

 

[ReadySteady98]

This one

 

[koalar]

These are a couple of mine both work but only just. You need a reasonably large flame not a pencil flame

Both use any size canister with a screw fitting better in my opinion as they are more common .

Wilko has the gas at £2.50

But I couldn’t find a cheap torch in the UK.

There’s a few at the £6-7 mark on eBay, I noticed some are push fitting though and some listings don’t say and it’s impossible to work out

B and Q have one at just over £10 but the spec also don’t say which fitting

Pretty sure you could find one under a fiver from China