Technical Panda 169

[maurajayne]

Any advice would be appreciated, my Panda 1.2 2008 engine management light came on last week, shortly after developed a misfire on acceleration, managed to get home and my neighbour suggested I take it for a blast down the motorway incase the cat was clogged.
Started to jerk but when it was warmed up ran good at 70 mph. Booked it into the garage and diagnostic came back o2 sensor, again I was advised to give it a good run to no avail. Next day light was back on, checked my plugs, checked the gap, took it back to garage they kept it 3 days and called to say it was fixed.
Charged me for a coil pack and set of ht leads. Drove a mile engine light came back on.
Thing I cant understand is my neighbour is a mechanic and the the garage said the same thing to drive it hard, but why if the diagnostic is showing o2 sensor have neither of them said to change it?
Cars done 84k regular service and timing belt/water pump done in may.
Seems strange that they reluctant to go with what the diagnostic reading said?

 

[jrkitching]

Charged me for a coil pack and set of ht leads.

Why??? That's just fault finding based on substitution and guesswork; generally a waste of money, particularly on a modern car with electronic diagnostics.

Seems strange that they reluctant to go with what the diagnostic reading said?

I'd agree. Changing the upstream O2 sensor may be all it needs. A quick lambda check should confirm a dodgy O2 sensor without dismantling or disconnecting anything; surely all garages these days can do a simple emissions test?

IIRC both O2 sensors are the same, so swapping with the downstream sensor is also a diagnostic option; though probably easier said than done if they're well corroded in.

You can buy a quality replacement sensor here.

I've also attached a copy of the current UK NTK sensor catalog as it's not immediately straightforward to find - it's a useful resource.

 

[maurajayne]

Thanks for your reply, seems crazy right?
I have no idea, the more I think about it the more annoyed I'm getting.
I wasnt asked if I want the parts changed because I would have said no unless it was the o2 sensor, think I'll make a complaint.
It just passed its emissions the week before for the mot, same garage.
When I think back I can recall maybe twice over the last couple of months a slight hesitation so maybe that was a warning sign.
I dont pretend to know a lot about cars but i can find my way round the basics. Not sure I'll have the strength to undo the o2 sensor, guessing ill run it till hot and try undo it? They look easy to get to right on the front, so your saying they are both the same part number?

 

[maurajayne]

Thanks for info I see from the catalogue they are the same part.

 

[A3jeroen]

Then again: The code could say that the O2sensor reads an unexpected value due to a plug not firing or an injector not injecting enough (or even a vacuum or exhaustleak).
Just the fact that the sensor is mentioned in the code doesn't automatically mean it's at fault and must be replaced.

gr J

 

[maurajayne]

Ok thank you, I'll check that out.

 

[koalar]

Then again: The code could say that the O2sensor reads an unexpected value due to a plug not firing or an injector not injecting enough (or even a vacuum or exhaustleak).
Just the fact that the sensor is mentioned in the code doesn't automatically mean it's at fault and must be replaced.

gr J

I could be wrong but think every error code relating to the O₂ is the O₂ or wiring to the sensor


Such as

O2 Sensor Heater Circuit Malfunction
HO2S Heater Control Circuit



There are errors the other way round like Fuel Trim Malfunction which could be Vacuum Leak or faulty O2 Sensor.

 

[DaveMcT]

O2 sensors will get sooty when sparks are misfiring - ECU sees the unused oxygen and richens mixture causing a the O2 sensor to get sooty. Having "normal" coils its likely the ECU does not directly see a coil fault.

Coolant temperature sensor can cause problems if its not indicating when engine is at running temperature. ECU continues to run rich sooting up the O2 sensor.

If all are ok and its just clogged, up you need to do 50 to 100 miles on motorway with foot hard down. You *can* exceed the speed limit but indicated 80 on mine is 75 on the sat nav so no big deal especially when everyone else is going faster.

:devil:

 

[koalar]

O2 sensors will get sooty when sparks are misfiring - ECU sees the unused oxygen and richens mixture causing a the O2 sensor to get sooty. Having "normal" coils its likely the ECU does not directly see a coil fault.

Coolant temperature sensor can cause problems if its not indicating when engine is at running temperature. ECU continues to run rich sooting up the O2 sensor.

If all are ok and its just clogged, up you need to do 50 to 100 miles on motorway with foot hard down. You *can* exceed the speed limit but indicated 80 on mine is 75 on the sat nav so no big deal especially when everyone else is going faster.

:devil:

Foot down throttle position puts the car in fuel rich mode and makes soot.

If you want to "heat" the CAT for an MOT there is no need to speed. Just don't change up so early so the car revs slightly higher.


Doubt It will help in this case though. I wouldn't ever ask someone to speed.

 

[DaveMcT]

But if the car has had a life of slow town driving, a few late upshifts wont do much. The gas flow will be much the same as its controlled by engine power/throttle position.

If it's clogged, the exhaust has to be properly heated to clear the gunk. That means doing the speed limit on motorway and a bit more wont do any harm. Speedos under-read, etc, etc.

 

[maurajayne]

Well I took the coils off and the bracket, turns out I had a coolant leak, leaking right onto the o2 sensor plug, the plug is covered with coolant and right in the pins. I've cleared the code, gonna take it for a run and just incase the o2 sensor is damaged I've bought a new one.
Anyone got any advice on how to loosen the old sensor? I bought an offset socket from screwfix but its not tight enough, keeps slipping off.

 

[koalar]

Depends on what you have available oxy acetaline until red is the easiest

Penetrating oil, take for drive, more oil and so on.

Much easier if it's hot after a run.


Hammer on ring spanner as long as the flats aren't to corroded and under size.


Never had to resort to smashing the end off and socket with breaker bar yet