[maully407]

Hi guys,
been a member of this forum for a while now and the help i've had has been invaluable when i had my 307 and my 407, now ive got a 207 petrol 1.4 08 reg. i have the anti pollution fault on the display, and have had 2 fault codes on diagbox and they are p0132 and p0138.
P0132 fault reads upstream oxygen sensor signal and p0138 reads downstream oxygen sensor signal both have open loop, does this mean both oxygen sensors have failed? what are the chances of that if they have, are they cleanable or should i just replace them both for peace of mind, as stated ive just got it and dont want to be spending loads of cash on it straight away. i own pp2000, diagbox and the lexia 3 kit so reprogramming and clearing the faults once changed wont be an issue.
many thanks for any replies.

 

[Blow By Blow]

I've seen instances where contamination is the cause of oxygen sensors failing, specifically steam in the exhaust on vehicles with failed head gaskets. K series engines on Rovers being a classic example. That said if both units are reporting open circuit perhaps it's exactly that and you have a broken wire in the path.

Any signs of obvious damage, melted insulation local to the sensors perhaps?

 

[maully407]

Thanks for the reply blow. Ive checked all the wiring and nothing seams to be amiss. Ive checked the plugs in the fuse box next to the battery and all the terminals are a nice shiney silver so no rust or water in them. I did receive one of my sensors that i sourced and replaced the top one that is situated in the top of the cat. Did a diagbox fault read and clear and now that one is not showing up as a fault anymore. Hoping the lower sensor comes tomorrow so i can replace it. Will keep posting till everything sorted.

 

[Blow By Blow]

If it does turn out to be a double simultaneous failure, be mindful that it's unusual, though not unknown. Keep an eye out for any other potential faults providing contamination into the exhaust, such as loss of coolant or increased oil consumption, that might be indicative of early signs of other failures of the engine. If contamination continues it could result in a costly catalytic converter failure.

 

[maully407]

hi blow, checked for contaminants on the sensors and no unusual residue or contaminants present.
i have replaced the bottom sensor and cleared the faults but not tried the car yet, i will post events on here as things happen.
engine fine no unusual amounts of oil or water being used, no leaks as far as i can see.
will keep posting.

 

[maully407]

after buying 2 lambda sensors and fitting them clearing the fault codes and driving the car the faults are back again.
they still are p0132 Upstream oxygen sensor signal and p0138 downstream oxygen sensor signal, both are reporting pen loop (conditions for switching to a closed loop not yet satisfied).
any help on this most appreciated.
thanks to blow by blow for his suggestions.

 

[WillNZ]

For both to be reporting open loop at the same time, I would be checking the wiring looms to both sensors has not been damaged. Also check wiring/plugs to the ecu for bad connections/corrosion/water.

 

[stripe88]

cant you just reset everything with your diagbox, seem to remember sensors run on pre set settings until warmed up, then the ecu or bsi does its stuff.


also check plugs in fusebox.

 

[maully407]

thanks for the replies guys,
ive checked the plugs in both the ecu and fuse box, all ok no signs of water, rust or broken pins.
ive checked the wiring from the sensor end back to the ecu plugs with a volt meter on a continuety test and all four wires from each sensor plug emit a beep when probed.
ive reset the fault codes using diagbox the car starts and drives ok till i turn off the ignition but when i go to use the car again the fault comes back.
dont think theres much more i can do but contact an auto electrician for help.

Also can an administrator add me to the planet map. i can do middlesbrough and around a 10 mile radius.

 

[maully407]

Well, would you believe it went to work this morning, got in the car and started her up expecting the dreaded anti pollution fault to flash up and lo and behold Nothing, no beebing no flashing of warnings and no eml light on. I swear that the car must have gremlins playing tricks .
Anyway im keeping fingers crossed its sorted its self out.

 

[IanML]

If not, I would suspect the coolant temp sensor.

 

[maully407]

now mate,
how would the temp sensor throw up oxygen sensor faults.

 

[reliable406]

I think he is saying that as the sensors will stay open loop till a set temp is reached so the sensor could be giving duff info not all faults are bad enough to throw a code.

 

[IanML]

Just so, and thanks for replying on my behalf - I missed the question.

 

[maully407]

ah, thanks for clearing that up "reliable".
i did notice that the temperature gauge took a while to start moving but didnt know it would effect the oxygen sensors if faulty i always thought it was to only show the coolant temperature.
as im typing this ive had a few issues but now seam to be sorted ranging from bsi faults to no acceleration response to temp gauge but all were sorted by removing the throttle body taking it apart and cleaning the contacts and insides very gently with a micro fibre cloth.
who would believe that this simple task would solve all the above issues.:thumb:

 

[IanML]

i did notice that the temperature gauge took a while to start moving but didnt know it would effect the oxygen sensors if faulty i always thought it was to only show the coolant temperature.

It performs several functions, including determining when the engine is fully warmed up to control the air/fuel mixture, and is taken into account by the fault detection system.