Don't buy cheap O2 sensors off eBay

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Don't buy cheap O2 sensors off eBay

Postby Finny19 » Wed May 17, 2017 11:26 am

So my car threw the code P0030 last week, referring to an issue with the pre-cat O2 sensor, made sense considering I had only achieved 400km from the last full tank . Removed the old one to get the part number. Bosch and Denso list them for $200+ a piece, yikes! Found cheaper unbranded one from an eBay for $75. It's a simple small part, surely price won't affect quality too much, maybe it'll just last shorter than an oem one.

Received in the mail, wrapped in a plastic bag with two torn cardboard pieces either side for "protection". Went ahead installing it, erased the previous codes and started the car. Got two codes, P0030 again and P0032 (O2 sensor circuit too high in voltage). Went to compare the new and old senors. The difference was the wiring. There are four wires: a white, a blue and two blacks. The two blacks are for the heater circuit. The two black wires on the new sensor were on the bottom two pins of the connector, THE OPPOSITE to the OEM one. Even after taking the new connector apart and swapping the wires i got the P0030 code back (likely the wrong wiring had fried the new sensor)

I am unsure if this has caused damage to the heater circuit, I have read the P0030 can also mean the relay for the circuit is busted or even the fuse within the ECU (meaning I'll need a whole new one)

For now I have plugged the old sensor in place while I get a refund from the ebay seller. But hope this serves as a useful warning to anyone with the same issue
Last edited by Finny19 on Sun May 21, 2017 2:25 pm, edited 1 time in total.
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Re: Don't buy cheap O2 sensors off eBay

Postby robo498 » Wed May 17, 2017 4:14 pm

Dam ! :angry2: hope all is OK with the car. I saw on the net people clean the O2 sensors, maybe worth a try? Best of luck. Robert
Last edited by robo498 on Sat Jul 15, 2017 9:57 am, edited 1 time in total.
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Re: Don't buy cheap O2 sensors off eBay

Postby teK-- » Tue Jul 11, 2017 2:18 pm

After Subaru quoted $500 fitted I went for a Denso it was about $100 shipped from USA. Hope your car turns out ok.
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Re: Don't buy cheap O2 sensors off eBay

Postby Daniel33 » Mon Jul 31, 2017 1:24 pm

Thanks for the heads up. I am waiting on a delivery of the cheap fleabay ones now for a r'wthy. I will be checking the wiring!! I bought both, perhaps I will just replace the pre-cat one, as that was the only code showing.

Just on that, once the OBDII code is cleared, how does the check engine light get cancelled? It is still on, even though there are no codes.
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Re: Don't buy cheap O2 sensors off eBay

Postby riblit » Mon Jul 31, 2017 10:53 pm

Any update?
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Re: Don't buy cheap O2 sensors off eBay

Postby Daniel33 » Fri Aug 04, 2017 11:31 pm

Well, I put the two new sensors in the car after checking the wiring arrangements, and they fitted fine, runs fine-ish. (It needs the heads done.) The AFR sensor heater circuit tested the same resistance as I recall the original had before I fried it. I didn't think to check the rear O2 sensor before I fitted it. It is still throwing a code, but intermittently, so I think it is a connection issue. I will unplug them both and put some conductive grease on the pins. This worked for my daughters' Forester. Will know more next week as it goes to get registered. The dash fuel useage calculator doesn't seem to be working though, and the cruise light is still flashing, so I think there is more to the issue with my son's car.

Is there a common fault that this symptom points to??

Daniel.
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Re: Don't buy cheap O2 sensors off eBay

Postby Daniel33 » Sun Aug 06, 2017 1:51 pm

Well, after I said I checked the winring, I only did the front sensor for the roadworthy. The back sensor I put in in a rush the morning of the second check, WITHOUT looking at the wiring, and of course, it was backwards.

The CEL stayed off after a reset to pass the second test, but came on again after a few k's.

So, this morning I fluffed around changing the position of the leads, and re-fit the sensor. Cleared the codes, and am yet to reset the ECU to confirm whether or not it is OK.

Moral.....LOOK first!!
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Re: Don't buy cheap O2 sensors off eBay

Postby riblit » Sun Aug 13, 2017 5:41 pm

Daniel33 wrote:The dash fuel useage calculator doesn't seem to be working though, and the cruise light is still flashing, so I think there is more to the issue with my son's car.

Is there a common fault that this symptom points to??

Daniel.

Seems to be that way. The fuel usage calculator will be a function of road speed and fuel flow, both available to the ECU.
Does "not working" mean no display?
A flashing cruise light means the cruise control has been disabled by the ECU, usually in response to a CEL. Have you checked for any DTCs?

What year Brumby?

John
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Re: Don't buy cheap O2 sensors off eBay

Postby Daniel33 » Sun Aug 13, 2017 8:58 pm

The trip computer might have a bad connection, as it is working now...but I have the CEL back up. Codes from both sensors now.

I am in communication with the ebay seller to obtain a refund......I hope!! They apparently have sent me a rear sensor which is exactly the same as the one I purchased, in other words, just as faulty!! :shock:

It is a 1991 twin headlight model.
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Re: Don't buy cheap O2 sensors off eBay

Postby riblit » Thu Aug 17, 2017 11:11 am

Daniel33 wrote:I am in communication with the ebay seller to obtain a refund......I hope!! They apparently have sent me a rear sensor which is exactly the same as the one I purchased, in other words, just as faulty!! :shock:

It is a 1991 twin headlight model.


Don't forget the sensors respond to a condition, the sensor code doesn't necessarily mean the sensor is faulty.
Have you looked at the sensor outputs?
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Re: Don't buy cheap O2 sensors off eBay

Postby Daniel33 » Fri Aug 18, 2017 1:21 am

Nope.

How would one do that? I am told not to test the resistance of the signal circuit, as it is current sensitive. Would I probe the sensor signal output for voltage with engine running? What parameters would I use to determine the usefulness of the signal for the car's computer? Does each sensor have different values? What are they?

What is the ohmage of the heater circuit for both sensors? What are the voltage outputs of each at engine start, cold, then at temp, then, with engine warm?

Would they drop in resistance under use? Could I test the current draw of each sensor under load and before startup? Then, does the current supply fluctuate via PWM to accommodate for acceleration / deceleration? Would it be attenuated at startup on a cold engine to make for a rich mixture?

Essentially, how do they work, so I can figure out whether these are working?

Would it simply be better, (and easier) to get some non-shit ones with a warranty or from a reputable supplier, albeit for more money, instead of from some importer who has offered to refund me 60% of my purchase price....and I keep the shit ones!! lol. I think I will send them back!! Especially considering that non shit ones could be the difference between 9 liters per hundred and 12. Only need to do 1000 k's for the gooder ones to pay off.

Now, to find some gooder ones!!
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Re: Don't buy cheap O2 sensors off eBay

Postby Finny19 » Tue Aug 22, 2017 11:19 am

Hi all, thought I might give an update.

The seller found out that all his products were incorrect and that the heater circuit wires were in the wrong position on the connector.
Thankfully, I received a full refund and a bit extra for the trouble.

The dodgy sensor had not damaged my heater circuit, as i was able to test with a multi meter

My local Subaru dealer quoted roughly $500 for the DENSO part excluding fitment.
So I purchased a USA Walker branded sensor for $180 dollars online.

As soon as I installed it, the CEL reset itself and i have been drama free for the past few months. I can now use cruise control whenever I want :D

Now I'm getting 600~650 kms per tank rather than 350
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Re: Don't buy cheap O2 sensors off eBay

Postby Daniel33 » Thu Aug 24, 2017 11:46 pm

I am still hunting for a good unit. Where did you get the Walker branded one Finny19?
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Re: Don't buy cheap O2 sensors off eBay

Postby dan_ashcroft » Fri Aug 25, 2017 10:25 pm

I just picked up some genuine units (pre-cat AFR sensor) from Partsouq.com, USD $150-something each from memory.
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Re: Don't buy cheap O2 sensors off eBay

Postby Finny19 » Tue Aug 29, 2017 6:41 pm

Daniel33 wrote:I am still hunting for a good unit. Where did you get the Walker branded one Finny19?


Local seller on eBay, his auto parts store was only a 20k drive from my house so I went and spoke with him before purchasing.
If you're gonna buy on eBay make sure it is a genuine branded item. A lot of listings selling cheap ones say "stocked from a quality brand" but that's clearly just nonsense.

Go for a DENSO or Walker like I did, I went for Walker as it was $30 cheaper than the DENSO one and came with warranty.
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