I have apparently jumped the gun on throwing parts. I have 2007 xtype that has had a few issues since new, but nothing I couldn't repair on my own.
However the latest bug is dreaded "check engine light" is on.
I cleared codes and started fresh then Shortly after startup it comes on. P1646. I read oxygen sensors. Bought 4 of them and have to admit was unpleasant on 2 of them, but after completion I go to plug in and won't connect...then i read black and gray ends. Heated upstream (black) and gray downstream. Website claimed they were the same...NOT
I reordered 2 black upstream but light comes on still. If I clear codes while it's running it won't come back, but 1st start cold it does come on. I don't know where to go from here but shop won't be one.
anyone with suggestions? Really stumped

 

Hi Blondie42,
Sorry to hear of your troubles....but can I ask a few questions of you to help build up a better picture.

As you appear to be in the USA, can we assume you have a 2.5 or 3.0 V6 petrol engine?
On the cold start, how long before you get the CEL light displayed?
Is it immediately, if not is it seconds or minutes?
Does it appear during initial idling or when you start to rev the engine or move the car?
Can we assume you are getting the P1646 code reappearing, or do you have other codes that now appear?
Does the engine appear to be running normally....no misfires, shuddering etc?

You may have in fact fixed the problem already and the CEL light might simply be present as part of the normal warning process that may clear after the car has undergone 5 driving cycles without further incident.
Alternatively if you still have the error persisting, you might need to check the integrity of the wiring to the sensors to ensure no open circuits or shorts.

 

Thankyou for helping to try and diagnose this.
Yes we're in USA and engine is 3.0 v6 with 140k on odometer.
If I keep scanner plugged in and delete the codes with key in on position, NOT running, the CEL wont come on at all. If i start it normally and just sit in park, it takes about 10 seconds to come on.
As I noted previous, I didn't do good job of homework and believed that the sensors were all the same. Obvious now I know they are not. I reordered to get the black elect ends as they are supposedly the correct upstream (heated) type. They showed up in dark gray but the plug was correct and snapped in properly so I installed them.
As to running, it seems OK. Maybe drinks more gas than I recall. ( i did change plugs)The only other issue is I can't fill tank without using slow stream or handle keeps clicking off. I didn't think it was related. Maybe I'm wrong. It still looks great and runs great but CEL light is hard to ignore. If something serious happens i wouldn't know cause light is already on.....if that makes sense. Thankyou again.

 

What brand are the sensors you acquired?
There has been quite a few comments in prior threads about inferior aftermarket sensors throwing issues.

 

I have a 2007, 2.1L X-Type, and have similar problems. The upstream sensors have a grey plug and the downstream ones are black. In my situation, the engine light extinguishes and stays off for a week or so, comes back on, then will extinguish again after a couple of short trips. Then it comes on again - repeat, repeat, etc. It has been like that since I changed the front bank, upper O2 sensor a few months ago. I think I may not have plugged the grey connector in properly, but cannot be bothered removing the battery to access the plug, at this time. I'll get around to it soon (I hope).... Ensure you buy good quality sensors from good quality vendors. I received a Bosch one from the UK (after asking for a Denso one) and as both can be used, I am happy. Apparently Chinese ones are to be avoided due to having only a short life before failing, or so others have found. Good luck with sorting yours.

 

I've expanded your thread title with a brief description of the issue.

Graham

 

I appreciate your input and would like to hear your outcome. It is a difficult task on a couple of the sensors that is for sure. I may have unintentionally bought cheap sensors. But I believe it is sensors as it's the only code I get but I have a couple questions;
1. Is there a way to test sensor with multimeter to know before removal?
2. If, there was a chance upstream and downstream were swapped would I get the same code?
3. is there any other issue that would give me that same code?
if i erase code after it comes on (with engine still running) it wont come back. If thats helpful or not.
I would prefer to stay after this while my arms and knuckles are still bleeding than wait till they heal only to tear them up again.

 

Blonde. I just replaced my upstream bank 2 o2 sensor. Works perfectly. My advice is to buy good quality sensors. Rock auto.com has them for reasonable prices. I went with the Denso brand for like $80. They also have Bosch. Installed new sensor. Cleared the trouble code. And all is well. No more code or check engine light.

 

1. Yes, but only for the heater circuit, and the computer already does this test for you and should raise a separate code.
2. Yes, you have likely put the upstream sensor in the downstream location and vice versa, if you are plugging the upstream into the black connector. The computer will expect the sensor value to change as fuel is changed, and post cat the readings will not be correct. On the factory harness side, I believe that grey is the upstream and black is the downstream. Some vendors use grey for both on the O2 sensor side, so it is really the keys on the connector that differentiates.
3. It is possible that a vacuum leak on the rear of the manifold could affect the rear bank enough to trigger the code, but I think you would have other codes also and you would need other issues like an under-performing o2 sensor to participate.

The upstream sensor is a wideband sensor which returns a more linear voltage result vs the AFR, aka a lambda. The cheaper downstream is just a narrowband which switches quickly to high and low voltage as it crosses a specific near stoich AFR threshold.

 

I replaced mine and went through Rockauto.com. I didn't want to chance using low quality ones since the firewall side are not the easiest to get to or replace. I bought the NGK/NTK plugs and they came with the same color (gray) connector on both. I just unplugged and replaced one at a time to make sure I was putting downstream in downstream and upstream where upstream was.

I've done some bonehead things before and I could see myself doing this, because I almost did......so I'm compelled to ask....

Did you possibly screw the O2 sensors into the wrong spots (upstream screwed into where the downstream goes, etc..) on one bank or both? Swapping the connector plugs wouldn't resolve this if the "Up" is where the "Down" should be. You'd have an "Up" in the "Down" position plugged into the "Up", or an "Up" in the "Down" position plugged into the "Down" but the sensor is for Upstream. See what I'm saying?

I only ask because you got 4 of the same sensors and had them screwed in, only to find out two weren't correct. This is an opportunity for easy confusion since the sensors themselves are not labeled (aside from the colored plugs, if you're lucky to have ones that have accurately colored plugs and not just all gray).

 

I really appreciate the input here. I believe you may be right on mismatching. I ordered 2 black ones to correct it. I may have swapped unknowingly. I am hoping I can return them all and start over with Bosch sensors.
I seem to recall many more holes in the downstream sensor than with the upstream. Those had like only 6 holes. Hopefully that is correct. I will try again and report findings.

 

You are definitely correct. The downstream have more holes. The upstream sensors have 2 vertical holes at various points (maybe 4 rows) on the cylinders. The downstream have at least 4 vertical holes and a lot of rows.

I know you are going for the Bosch but the NGK brand has never done me wrong. I buy NGK whenever I can, spark plugs, sensors, coils, etc… and they’ve never failed. In case you need a back option, here are the NTK (NGK) downstream sensors on Amazon. Reasonable price too.

NTK 25607 Oxygen Sensor


Rockauto also has the NTK but for $62+ tax & shipping. They have the Bosch downstream for $71ea and upstream for $85ea. I don’t know why they list the upstream as an “economy” part but the downstream is “daily driver”. Pretty sure Bosch only makes one type of upstream sensor….anyway, let us know what happens!

 

Thankyou for the response. Ugotmale,..
I order ngk as you recommended but only upstream .I thought they were more important, and I couldn't find downstream number for ngk.
I did indeed have wrong ones in and thought it would all be good but alas, the dreaded P1647 still came on after about 5 minutes. The only code I get. So I have to assume the downstream are wrong, or not working properly? Bummer. I don't know what else it could be. Car seems to run OK.
if anyone knows ngk numbers for co2 sensors for 2007 xtype it would be very helpful.
I really like the car but the engine light is not OK. Hopefully downstream helps. I'm at a loss. Both mentally and financially. I need some success.

 

Yep, Blondie, I have finally bought a new upstream one for my repeating 1647 code. Hope this one fixes it. If not, I guess it also will mean venturing into the downstream work effort....

 

I wouldn't make the assumption the downstream are wrong, just yet, when you have a P1647. The P1647 (correct me if I'm wrong) is specifically referring to the "upstream" sensor on Bank 2. Fortunately Bank 2 is the radiator side! Makes troubleshooting a bit more tolerable

Anyway, now that they are brand new it is not likely the sensor is the issue. Considering the upstream are heated sensors, I begin to question connection and wiring. I begin to wonder if the connection at the plug is problematic and causing continuity issues. If the sensor is not getting consistent voltage due to, say a loose connection or poor contact at the plug, it is going to throw a code that there is a fault. So before I start buying Downstream sensors hoping to resolve the code problem, the next thing I would be focused on checking is going to be the connection at the plug. You'll want to check the prongs in the plug at the harness to make sure they are not corroded, missing, or loose causing a poor electrical connection. I would also be checking the wire off the wiring harness, tracing it all the way to the plug connector, just to make sure there are no frays or damage. You could reach out to a friend or someone (if your not electrically inclined - like me) that is handy with a multimeter and voltages. They could test the plug on the wiring harness to make sure it is consistently providing the right voltage to properly power the heated sensor.

Lastly, it is possible that the catalytic converter is the......well, the catalyst, of the issue. Since you have a 2007 it is very very unlikely the cat is bad. But, if there is an exhaust leak anywhere in the pipe - like at the joint where the cat bolts to the manifold - it will throw a code that either the cat is bad or the upstream sensor is out of range or not working. I say "will" like it is definitive, but the chances of a leak causing a code are greater than just "can". If the cats have been replaced before with replacement OEM cats, it seems the affordable replacement OEM cats don't always fit perfectly without some adjustment. So it opens the door for the possibility of an exhaust leak pre-sensor.

As for the NGK/NTK sensors and you not being able to find the downstream number - The link I attached in an earlier post were the downstream sensors for NGK (NTK 25607). You say you bought upstream NGK? As long as they weren't the sensors from that link to Amazon, those were the downstream.

NGK / NTK Sensors:
Upstream: NTK 25631
Downstream: NTK 25607

 

I greatly appreciate your taking time to help work it out. I indeed bought the 25607 thinking they were upstream, however it was my understanding the sensors with fewer holes WERE the upstream. If I got this wrong then I may be the problem.
I will get the 25631 and maybe I will get it right. I am embarrassed at how long this check engine light has been on.