I haven't posted or been back on here for quite a while, but I thought I'd share my experience with the oxygen sensor.

A couple of weeks ago driving along, the car started to feel really sluggish, as if there were no power, and it would only take off when I pressed the accelerator (and then it really took off), but once stopped accelerating so hard it was really sluggish again (actually like engine breaking). At first I thought I had fuel issues, so I pulled over, revved the crap out of it and it was fine.

After this has happened a couple of times, I replaced the fuel filter at the first available opportunity. After I did this, the issue still occurred, but again it could easily be 'resolved' temporarily by revving the car in neutral. I searched through this forum and found someone that had a similar issue, and it was the oxygen sensor. I ordered an oxygen sensor off Ebay (http://www.ebay.com.au/itm/NEW-4-Wire-Universal-Oxygen-Sensor-O2-Easy-Fit-Kit-/120738436183?pt=AU_Car_Parts_Accessories&hash=item1c1c925457) last week, and it arrived yesterday (I picked it up today).

Now, last week the issue was getting a bit worse, it was happening every time I drove the car. On Saturday on the way home from watching the new Batman movie the car actually cut out, stalled, and nothing could get it working properly when it was running. Luckily I was pretty close to home and it was 1am (I went to the 9:45pm session but we weren't even allowed into the cinema until 9:50pm due to a cleanup.

I should point out that even if the car was working, once it was warm the performance had dropped.

Anyways, as I wasn't home to receive the item I had to go to the post office. I just made it there, and back. I replaced the Oxygen sensor, disconnected the battery for a few minutes, then went for a drive.

Needless to say, no issues! It is running perfectly and feels much better :). To make sure it wasn't coincidence I idled it for about 5 minutes and drove around for half an hour, before it was stuffing up after about 2km.

So, if anyone comes across an issue in a 3rd gen Magna where:
- power loss when engine is warm
- engine surges, and no power unless you press the accelerator a fair way
- the feel as if the fuel filter is blocked#
- car runs bad unless you accelerate quite hard
- car runs rough and stalls when warm
etc

Then I recommend the oxygen sensor be on the list of things to replace. I put a # next to the fuel filter as it probably wouldn't hurt to do that if it hasn't been done in a while. Also a good time to clean the MAF sensors :)

I admit the car stalling is a 'worst case' scenario, and yes I know, it shouldn't happen! but it appears it can with the 3rd gen as I and others have found out. It could be a short in the sensor? I'm guessing in newer cars the ECU would just cut the signal and show an error light...

Yep O2 sensors can be a pain in the ass when they die because they usually peg at 0 volts and the ECU dumps fuel into the motor to "compensate", thinking its running lean.

But HOT DAMN that is a good price for an O2 sensor. Good find! I ordered one myself; for that price I'm willing to risk it being crappy.

Yep O2 sensors can be a pain in the ass when they die because they usually peg at 0 volts and the ECU dumps fuel into the motor to "compensate", thinking its running lean.

The 3rd gen Magna ECUs unfortunately won't show a CEL or diagnostic code for a bad oxygen sensor, although I believe that the USDM Diamante ECUs will. While the ECU does attempt to compensate for the lean signal from the bad sensor, there is a hard limit (known as a fuel trim limit) on how much extra fuel it will deliver (25% I believe in these ECUs).

The simplest test for a bad oxygen sensor in the absence of a multimeter or other test gear is to run the warmed-up engine with the sensor unplugged: if the engine runs better without the sensor plugged in than when it is, the sensor is suspect.

Many engines seem to run well enough with the extra fuel caused by a bad sensor that drivers quite often don't notice anything except the hip pocket damage, while other engines seem much less tolerant (as above).

For all I know it could have been faulty for a while. I suspect that typically the engines would seemingly run fine, like it did for me initially after the surging and revving in neutral. In this case it would probably just hurt my fuel economy. The interesting thing is it changed over the last couple of weeks, to the point on the weekend where I would classify it as undriveable. I'm glad I had the sense to reset the ECU, as I'm sure it was way out of whack!

When I was doing a search on here last week for the symptoms I noticed in some threads where people have replaced 'half' the car (besides the Oxygen sensor) and were still having issues, so I thought I'd mention the symptoms I had in case it would help others experiencing the same symptoms in the future. I honestly didn't think the Oxygen sensor would cause the issues I had, because as far as I knew the worse thing to come from a faulty O2 sensor is bad fuel economy. I'm sure others probably think the same. I'm glad I was wrong about that, and right with the solution!

This sounds like it might be whats wrong with mine. Crap fuel economy, high revs on startup & surging idle between 1100 & 1900 RPM.

Just bought one. Will see if this fixes me up too.

Thanks Burfadel: This is what we all need to know. Listing the symptoms and then the cure helps us all to get to know our cars so much better.

Just bought one. Will see if this fixes me up too.
How many km have you got on your car just intrested. thanks

185000km, I don't think it has been changed either. I don't have the same problems though.

Great to hear it ended up being quite a simple fix burfadel, out of curiosity how much mileage is on your car?

My car has quite high mileage... 340,000km! at least 260,000km of that was highway driving though. Since I live in Adelaide now I don't rack up the kilometres like the car used to. I thought the O2 sensor was replaced about two years ago by a mechanic, but looking through the records it looks like I was mistaken. Still, it had been replaced previously so it wasn't the original part (I think 340,000km is pushing things a bit). At a guess, it would probably have 160,000km on it.

I'm just glad it was an easy fix, and that i found these two posts (reply and a follow up) on here that led me to it:
http://www.aussiemagna.com/forums/showthread.php?t=91105&p=1443731&viewfull=1#post1443731
http://www.aussiemagna.com/forums/showthread.php?t=91105&p=1444168&viewfull=1#post1444168

Just remember to reset the ECU after you do it, to clear the recent 'bad learning'.

If it is the case that fuel was being dumped into the engine, effectively meaning it became flooded, I'm guessing I would have a huge carbon buildup? Might put in a fuel system cleaner and go for a longer highway type drive later this week to clear it out.

185000km, I don't think it has been changed either. I don't have the same problems though.


Just bought one. Will see if this fixes me up too.

Let us know how it goes! I think the stage that mine was at was worst case scenario, I'm sure that it could present itself at any level between working perfectly and the situation like mine was running at.

I've been thinking ECU until I read this thread. Had to ride the bike in the freezing cold this morning cause the stupid f@#$ing car has been getting worse and nearly left me stranded in the work car park yesterday. The mid range "drone" is also what mine is doing and really hard to start and keep running as if it's on 2 bloody cylinders. Yesterday was the worst with is cutting in and out on take off and jolting to the point where it felt like the engine mounts were gonna break. Once i get going it feels slightly sluggish but will sit on 100k's all day with the occasional miss. I have to ride the brake ( it's a manual by the way) at every stop keeping the revs up as it splutters and runs like crap. You've got me excited now, hope it's this simple and cheap to fix.

Yeah that sounds like it was for me when it was running at its worst! Except when the car started it was running fine, it was only when it was warm that it really got bad (and basically undriveable). I am guessing if you left it long enough carbon buildup could make for poor starting etc too. If the Oxygen sensor replacement does fix the running problem, I would suggest putting a fuel system cleaner through it and go for a long drive to clear up the built up carbon.

Do you reckon the excessive smoke on start up when it's running crap is the ECU compensating and dumping more fuel? This only happens when it's running like crap, when it smooths out the smoke goes away. Doesn't smell like oil smoke either. I'll get home from my hour long commute and it will run crap in the driveway until I rev it past the crappy spot where it's smokey. In the mood to put a match to it at the moment.

Oh, any one that's read any of my other posts would know it's on LPG.......and no, I'm not that stupid as to burn the stupid car.

It could be... In any case, if you haven't replaced the Oxygen sensor in a long time, if at all, it would need replacing anyway :). I guess if you turn the car off with it running with excessive fuel it would burn off on the next start with smoke. I never noticed smoke myself (in the cold mornings there is steam, but every car does that burning off the water in the exhaust), there could have been a bit of smoke mixed in with it. I do know the first time it happened and I revved to clear it (it drove bad just as I was pulling up to stop luckily) a friend I was meeting said it was blowing smoke when I revved it. When it was fine after the revving it didn't smoke though. In my case I think the sensor gave way pretty quickly. Probably 2 tank fulls where I was getting worse economy (come to think of it), and a couple of weeks since the first running rough incident. All I know is that the running crap got worse, until on the weekend it was pretty much a constant thing when warm (it was impossible to drive). Luckily I had already ordered the sensor. The intermediate between when I first noticed it and it being undriveable on the weekend sounds like what everyone else here has described, so I hope you and they have success after replacing it too.

It would be good to hear back about whether people have success after replacing the O2 sensor (remember to disconnect the battery to reset the ECU, and also remember it takes a little while for it to relearn). If it's a common resolution to the similar symptoms then it would be important information to go in the fix section maybe?

Will definately post my findings. Ringing around today didn't get me any possible solutions but a few minutes on here and I've hopefully got it sussed out......we'll see soon.

I suppose that the catalytic converter might possibly become clogged with soot from the rich running if the car was run for an extended period with a dead oxygen sensor. I don't know how likely this is.

This sounds like it might be whats wrong with mine. Crap fuel economy, high revs on startup & surging idle between 1100 & 1900 RPM.

Oxygen sensor(s) only come into play when the engine has warmed up, so won't affect cold starts.

I seem to recall the idle speed controller being implicated in some cases of surging idle.

Oxygen sensor(s) only come into play when the engine has warmed up, so won't affect cold starts.

I seem to recall the idle speed controller being implicated in some cases of surging idle.

The 380 has a fly by wire throttle body totally controlled by the ecu. My other theory is the throttle body itself as it has been bored with a bigger butterfy & thinking the internal return spring maybe too weak with the blower airflow!?

The 380 has a fly by wire throttle body totally controlled by the ecu. My other theory is the throttle body itself as it has been bored with a bigger butterfy & thinking the internal return spring maybe too weak with the blower airflow!?

Sorry, the nature of your alternate theory is beyond my knowledge.

I would still check out the oxygen sensors just to make sure that they aren't making things worse.

I believe the 380 has two Oxygen sensors, both the same (one inside the engine bay and one underneath). If are they are really bad they should trigger the CEL light in the 380, but the ECU only knows to do this if it is exceptionally bad. If the sensors haven't been replaced yet its probably about time to do it in the case of 380's anyway, especially if the car is post 100,000KM.

The really bad running symptoms I suggesting is for third gens, I'm not sure whether the 380's would result in similar symptoms or whether you would simply get worse fuel economy and a CEL if they go bad...

I got a PM today of a member on here thanking me, they said it made a huge difference replacing the sensor. It's good to hear that someone has found the thread useful! If others have replaced the O2 sensor and also found such a huge difference it would be great to hear! It sounds like it may not be an uncommon issue...

Thought I'd give you all an update. Ordered the oxygen sensor that burfadel posted the link to. Ordered it last wednesday night and it turned up today. Got home from work at 5:30pm on the bike today as a mate turned up in the driveway. Had a quick chat, got rid of him, changed out of my bike gear into something more comfortable for climbing under a car, unlocked the shed to get all the tools and then got to work. Well basically by 7:10pm I'd got the car going, went for a quick spin and even had dinner after putting everything away. I'm as happy as a pig in shit right now! The cars got all it's power back, even to the point where it feels like you could drive around town all day leaving it in 5th gear. To any one out there mucking around with every thing else, why not try this $42 gamble first before possibly spending much more unnecessarily on other parts. Thank you burfadel for this very helpful (well, in my case anyway) thread.

Thanks, no worries! I'm extremely pleased with mine, I took it for a 45 minute 'highway' drive the last weekend, I think it even ran a bit better after that! Which is always a good thing to do with old and new cars if they've been doing lots of short runs. It's kinda funny that you don't realise how bad it had been running until you fix things like this and it runs great!