Hi everyone, I am replacing my upstream O2 sensors on my 2005 DB9. I've triggered several emissions warning lights, reset the codes, had the codes return, etc. so I'm pretty sure these upstreams are shot. My issue is the actual removal of the current O2 sensors. As seen in the pic below, they are routed behind hard lines with not enough space to slip the connectors behind the lines to free up the sensor for complete removal. The only option seems to be to cut off the connector ends, but if I do that I can't put this back together with the old sensors (which allow the car to drive) if there's an issue with the new aftermarket sensors not taking, correctly.

So for those of you who have removed your sensors, did you get to them from the top of the car and how did you remove these things without cutting them apart? My passenger side isn't too hard to get to but I know my driver's side is going to be a pain in the butt. Thanks for any detailed guidance you can lend to a weekend warrior.

 

Buy a mirror and look up under the manifold. The long black channel exposes those wires, which have a small clip holding them in place.

I use connector pliers to get in and out of tight spots.

 

I know exactly what you’re talking about as I replaced all 4 in my V12 last summer. I ended up removing the terminals from the connector and pulling the harness from behind the hard pipes. I hate cutting wires if I can avoid it. It’s pretty easy to do with a small pick or pin extractor tool.

 

Thanks guys and good to hear from you again, Supraholic. I’ve already exposed the connectors and coolant lines underneath the manifold by removing the black covers. The issue now I getting those connectors out from behind the hard pipes when trying to fully extract the o2 sensors, as there isn’t enough clearance to pull them behind those pipes, as they’re routed now. Supra, are you suggesting you were able to disconnect the o2 wires from their end connectors somehow so you could pull the remaining behind the hard pipes? I’ll have to learn how to do this.

I imagine your replacement o2 sensors were just routed on top of the hard lines, not behind again as they originally were?

 

Exactly. With the pins extracted from the connector, you can easily pull the harness from behind the hard pipes.

I routed the replacement sensors harness through slits in the black housing cover to retain the clean look. No way I was going to feed them back behind the hard pipes...

-Dan

PS. If you’re interested, I could post a quick vid this weekend on how to pop the pins out of the connector housing. You’ll be amazed how easy it is...

 

Hey Dan, thanks for the confirmation. I didn't even know that you could separate the pins from those connectors, but like you, I'd like to hold onto the old sensors without cutting them, so I'll do the removal just like you did. If you're willing to do a video to show me that'd be great! I'll set into it this weekend and get these old ones out and the new ones in.

For any readers, note that I broke one of the covers for the coolant lines and o2 sensors connectors when pulling it off. The plastic had become brittle over the past 15 years and the tabs just didn't bend as they likely once did. Thankfully, the part is only $10 and is part # 4G43-6793-AB in case you want to have one or two on hand for your replacement.

 

Okay update. This has become an unenjoyable project. I ordered the O2 sensors that Rockauto identified as the compatible parts for my vehicle, Walker Part # O2 250-24001. This may have been a mistake and following Dan's parts numbers might have yielded better results. I thought Rockauto may have tested these for compatibility and could vouch for them, but I'm not saying they didn't either.

I replaced all four upstream sensors this weekend. Dan... I figured out the red tab in the middle of the connector needs to be removed to de-pin them, but this was really hard for me to remove on all of the sensors, so I had to destroy two of them on removal. I couldn't seem to find a repeatable way to remove that piece. After replacing all four upstream sensors, I cleared the emissions codes on the vehicle and started the car. Things started out okay on the first start and then I restarted the car to back it out of the garage since it was smoking a bit from the cats, burning off the PB blaster I suppose, which eventually went away.

After a few minutes the car started to have a rough idle again as it did before the repair. I also had a blinking rear defroster light for some reason as well as a low voltage warning on the cluster. I let the car idle for a while while I worked with the OBDII scanner and eventually the car really started to idle rough and then forced a shut-off on the cluster, saying the DSC need to be serviced. The car was able to be restarted as normal, and I ended up with a few codes after this:

Module 1:
P1656 - CAN link pcm/pcm circuit network
P2106 - throttle actuator control system - forced limited power

Module 2:
P2105 - throttle actuator control system - forced engine shutdown
P0606 - control module processor
P1797 - CAN transmission control module to engine control malfunction

After a few minutes the car did the same rough idle and then forced a shutdown, again. Interestingly it says the emissions system needs service on the cluster, but I don't have the same codes as I did before, pointing to the O2 sensors. I now have more problems than I did before the repair though and a lot of codes that don't seem to relate to one another. I am wondering if these new sensors aren't compatible with my car.

PLAN: Right now I'd bring the car to Aston Martin, but I expect even the diagnosis would cost more than to just get AM genuine sensors. I also expect they might blame a lot of my troubles on the aftermarket sensors, so I think it is best to just replace with genuine AM parts and HOPE my problems are resolved, otherwise I'll be giving the car to AM with all genuine AM parts and hopefully they can fix my issue.

Does anyone have any unique ideas as to what I'm seeing here and a better course of action? Either way I will post updates based on what I find by the end of this, since this hasn't been a straightforward fix.

 

Hi Matt. Thanks for the idea. I read this thread https://www.6speedonline.com/forums/...limp-mode.html from another user that had almost all the same codes as me, had his car die out and was able to immediately restart it, just like me. His ended up being a bad battery, like you are thinking.

So I pointed toward that today, measuring my battery at 12.5V at rest and 14.6V consistently while the car was running, several times. The car turns over quickly each time I start it, as well. The battery is a Jaguar battery, so it's not the original battery I don't think. This isn't to say something couldn't be wrong with the battery, it just doesn't show any usual signs. Since I wasn't convinced the battery was bad, I pulled the negative terminal and reconnected it, then cleared all codes to see how the car would act with the PCM reset and I fired it up.

This time the car had the rough idles every 4-5 minutes or so where the RPMs drop for a few seconds like it did before the O2 sensor replacement, but it never went into limp mode this time. During these extended idles, the scanner showed no misfires on any cylinder. The codes that returned during 15 minutes of idling are as follows:

Bank 1:
P0705 - DTC-- Transmission Range Sensor Circuit Malfunction
P1000 - DTC-- System check not completed since last memory clear
P1797 - DTC-- CAN transmission control module to engine control malfunction

Bank 2:
P1000 - DTC-- System check not completed since last memory clear

I also have another emissions warning on the cluster, but I don't see any of these codes relating to that. I should also share that while watching the O2 sensor volt readings, all downstream sensors were steady at about 0.8xx volts while the upstream sensors kept jumping all over the place from 0.2xx to 0.8xx. Not sure if that's normal.

Sorry for being so long-winded. I'm just wondering if all of this information sets off any light bulbs with anyone? I think my next step is to pull the battery and see if a local parts store can run some tests on it to see if they find anything wrong with it. Any thoughts?

 

You definitely won't have any misfire corrections stored after the battery disconnect, and you might not have had any stored before either.

You might be having misfires that aren't being detected.

You have low mileage for coil pack failure, but I have a friend with a 2005 DB9 that recently needed coil packs at about 15K miles.

 

Thanks for this information. At least that gives me an idea to stop looking at the O2 sensors as the culprits.


For my knowledge to know when the coil packs need to be replaced, I'd show misfires if they're failing, correct? I monitored the car for misfires during a drive cycle and no cylinders showed any significant misfires in a 20 minutes drive, but I fully expect the coil packs to be needing replacement eventually, like you said. I think all cylinders were less that 0.3%.

 

My point was that without stored misfire corrections, you don't get accurate misfire counts with your scan tool.

In my case I had a lumpy idle. Very few misfires reported but no misfire corrections stored. Once I did the misfire correction learn cycle, lots more misfires showed up.

 

Interesting! I didn't expect to see many misfires during idle but didn't want to drive the car yet until I'm confident I won't go into limp mode.

Was your idle consistently lumpy or every few minutes, like mine? Did the misfire correction learning help with that issue, or what did you do to cure your lumpy idle?

 

My lumpy idle got progressively worse over time. It was a regular occurrence at stop lights. Never really noticed anything out of the ordinary at speed. No CEL.

Scan tool showed very little misfire activity. Then I did the coast down learn procedure, and lots more misfires showed up.

Replaced all the coils and plugs to solve it.

 

Thank you for that insight. I didn't expect the misfire correction would show MORE misfires. I'll make that a priority when I can get this thing safe to drive again. Thanks for your help so far!

 

Good reading at https://aston1936.com/?s=misfire

Hopefully your issues all come back to the O2 sensors.