Hi All

I had a faulty o2 sensor which I replaced with a non genuine off ebay, after a short run the engine managent light came on again saying that the o2 sensor was too slow to respond

I then purchased a denso front o2 sensor with the same part number as the original but after installing the car is jerky in mid range

Ticks over OK and is OK at high revs

I have drove the car for 10 miles to see if it would adjust itself but its still the same

I checked using delphi and it shows the o2 sensor as lean

Is it possible the none genuine sensor has confused the ECU?

The car stops jerking when the front o2 sensor is disconnected

 

have you at any time reset the ECU to clear it oif codes and learned values??

 

I disconnected the battery for 5 minutes

Cleared the fault codes relating to the slow o2 sensor

No fault codes have returned but the car is still surging

what's the best way to reset the ECU and relearn values ? I have seen that many conflicting ways online I'm confused

2003 wrx

 

You need an OBD II tool on a new-age car and newer....

 

If when connected its Leaning out then there is perhaps some resistance in the cable or in the connector that drops the voltage
I'm afraid even a Denso manufacture (Hungary/Cech Rep/Ukraine or worse)
wont always keep all sensor output to original Japanese Spec. Id try an older SH /other original sensor first.

And of course when fitting you do need to keep the unplugged lead disconnected ,
it would not be the first time that someone put a snake coil into a lead , and caused a strand cable break ,
which might have happened to yours if it was returned by someone.

Bank 1 (Front o2 sensor ) Low voltage = appx 0.1 Volt for Lean mixture ( lots of unburned oxygen in the exhaust)
Higher Voltage appx 0.9 volt indicates a Rich mixture low unburned oxygen in exhaust

Id expect you will get a Engine control light as soon as you run the engine with O2 disconnected (open circuit). The engine will also run Rich if the O2 is disconnected.


If OBD II is telling you mixture is too lean, then of course timing will be pulled to protect against knock / detonation
and that might well happen if the Front O2 sensor says it sees less than 0,1 Volt caused by a high resist in the cable or connector.
but the wrong lower voltage its possible if you have made a Decat modification ( more flow = lean out )

You'd get the same effect if you change the turbo and don't change the map for more injector duty cycle.
I have had that happen and it runs like a dog , my solution was to pull the + lead off the battery terminal ,
and then stay off the boost. So some short term learnt fuel trims values can be reset.

wish you success finding the cause.

 

Hi

When fitting the new cable I was very careful not to damage, I was in a pitt so it was no problem with access

The car is stock with no mods

The Denso sensor that I got on ebay had the same part number and had a subaru label attached which looks genuine

Should I give ecu explorer I try to see if a reset helps ?

 

Just to confirm part number should be 22641AA042 for the front A/F (Air/Fuel) sensor

 

Hi Don

Yes that's the correct part number

I have attached a picture of the packaging

I will give delphi a try to see if I can see the voltage of the sensor

 

Looking at the picture, I've never seen the genuine item labelled like that, as Subaru doesn't call it an Oxygen Sensor, as such, it's an Air/Fuel (A/F) Ratio Sensor.

 

Chris , I agree with Don , If it does not look exactly like this , and I mean exactly
also to include the 2x cable attach shown better here then its likely to be a copy part
If it is one then these "aftermarket" items usually target the higher volume models.
The worse thing about this is It might still work , but perhaps only serve to confuse you
if it is scaled differently or has slightly different output.





Also if you look at the labels printed on the box shown by Don you will see they have symmetrical
corners , this type of label is printed on a high volume printer using a large diameter special roll
The roll stock is pre printed for Subaru , you will also see the font and thick print is from a label printer.

The label you show has a rounded corner , ( multiple labels are printer on a sheet ) this fact
and the Font plus the wrong description make me suspicious. Most fakes are done on copiers.

Added to this I would say you did not receive the part in its original box , I say this because your poly
bag is not fresh and clear but has either turned translucent or has done so through time due to exposure
to UltraViolet light . If you see any other differences in the connectors wrong colour plastics
poor injection mold polypropylene swarf rests, Non heat resistant protective mantel then its a fake.

I used to work as Quality control manger for Tyco Electronics Automotive in Germany , and I have seen lots of this sort of thing
even sold into Main Dealers ( who then unscrupulously use the parts to increase profit margins ) but when something goes wrong
you could be sued and the blame goes up the tree to the original manufacturer , and the buck used to stop at my desk

Let us know if you get it fixed

 

Thanks for the pictures

That's a great help, I wondered why the seller wasn't promoting it as being a Subaru part ( I found it by searching the part number )

I was wondering why I had to drill the small bracket as the 2 plastic clips were bigger than the original

Makes perfect sense now after seeing the correct packaging

 

This is the answer from the seller on Ebay , I told them I shown the picture to the local Subaru garage and they said it doesn't look genuinehi We sold over 180pcs on few auction not have any one issue The sensor is GENUINE SUBARU so how they can see pictures and say is not if the factory sold all same for other Subaru ? Any way send back

 

Do some logging after you have reset the ecu, the voltage of the sensor with ignition on but engine not running gives us an idea if the sensor is dud or not.

 

As I said , it may work and indeed if I see Subaru's sub-crontractors people like Denso / Summitomo making them, I would also normally trust them especially if the item is from Japan. But from other locations other unknown named contractors, located in "third countries" like Malaysia, Thailand , Ukraine, China who may very well have historically produced them, or something similar spec for other car models but you just don't know and many Ebay dealers just cannot tell if they were provide fully approved Subaru parts.

In order to be sure if the part you have does not work. First you should try a borrowed / second hand original or you have buy another one from Subaru looking carefully for the box that Don showed you. Test and confirm the fault has been fixed and then you can wave a finger at you ebay supplier. Anything else which has not been substantiated is a not fair on them , they may be unaware. The right way to go about it is to ask for a replacement first. If a part has been returned to stock and re-issued somebody may have hoodwinked them. Always be careful to see if your package is original sealed.

If you buy at the dealer chances are the smaller ones will order it in and you will have to wait (and that's great ) as the part comes from a UK/EU central store, or even from Japan. If you go over the counter and it comes of his shelf do the checks Don & I showed you first.

For low cost things like pollen air filters / plastic fittings / interior parts you can take a ebay risk , but for technical items that concern safety of your engine ( and this one is critical ) don't take the chance.

Keep the feedback coming we need to find out , what finally fixes this it helps everyone on here.

 

Here's the logging info for the sensor

The 1V is when the engine is off and ignition on


​​​​​​​

 

Something very wrong there an o2 sensor should switch between 0.1v and 0.9v at tickover. Plus it is also very garbled it should be a cleaner switch.

 

No wonder it Jerks , looks like extra volts are arriving , could be a mess on a controller board , supply volts are dropped by switched resistors if one is breaking down ( eg Poor solder joint) this sort of thing could happen. In which case it won't matter which O2 sensor is in the circuit they all wont work. Im afraid you will have to work backwards in the circuit to find the fault.

 

Voltage doesnt look too high, did you reset the ecu?

 

Couple of things ,

Question on 1509Joe / Stig are we dealing with a wide band signal on this front O2 ? because if we are then the range will be higher than 1 volt. Maybe as high as 4 volt in service in very lean mixture.

A parts search on the 22641aa042 reveals it was fitted to vehicles upto 1997 to Feb 2003 on EJ series engines 2.0L but also on

Forester 2.0i 170bhp EJ205
5/2000 to 4/2001 Forester 2.0i 177bhp EJ205
4/2001 to 5/2002 Forester 2.0i 177bhp EJ205NW / EJ205NX
9/2002 to 5/2002 Impreza 2.0i 218bhp Estate EJ205
9/2000 to 12/2002 Impreza 2.0i WRX 224bhp EJ205
10/2001 to 8/2005 Impreza 2.0i WRX STi 265bhp EJ207
11/2001 to 8/2005

Here are X ref supplier part numbers

ACDelco - 213-2843
Airtex - 5S4302
Bosch - 15537
Denso - 234-9011
NGK - 24659
Subaru - 22641AA042
Walker - 250-54004

 

out of curiosity how much did you pay for it? they retail for about £250 from subaru themselves for comparison


partsouq has them at $253
https://partsouq.com/en/search/all?q=22641AA042

 

Don't understand your question. The JDM T/S cars have a semi wideband iirc but this is a UK WRX I think so should give out normal readings.

 

ICP sell for £102.50 (Denso supplied I'd imagine)
https://www.importcarparts.co.uk/par...y=&searchPart=

 

Signal volts in yellow

 

Take it the second set of graphs is the T/S JDM car Don

 

Both taken from the MY03/04 2.0T UK/ European ECU pin out and I/O signals diagrams
A couple are sensor heater readings

Same as on complete pages listed here for MY01
https://www.scoobynet.com/general-te...u-diagram.html

 

Interesting going to have to look into that.

 

I paid £69 with Free delivery

I thought it was a bit cheap but then just thought it was an old stock item

I'm going to give importccarparts I try, I have bought from them in the past and the quality is good

I'll update in a few days

 

Got the new sensor from importcarparts and fitted today, car is back to normal and running great

I've attached some pictures of the sensors side by side and screen shot from delphi ( new sensor from importcarparts is on the right side)

 

Another picture of the faulty o2 sensor , the securing clips are white instead of grey

 

Really interesting for me , I was not able to pin down 234 000 9170 for what vehicle you actually received that Denso part # for ( even if defective or not )

And I would need to see the Denso # 234-XXXX on the other side of you new sensor photo to see if it matches Denso s part finder confirming itfor you car /year.

However

Subarus # 22641AA042 New part on crimped sleeve can be found using Find My Part (densoautoparts.com)

For your 2003 year = Denso part # 234-9011






Tip For information to find cheaper / alternative supply SAAB PART NUMBER is 32005978

2005 SAAB 9-2X used the same EJ205 engine

Note the quality of metal work on the new part that works for you on the right