Ok, so i went to the dealer back and forth over the last month because my check engine light has been coming on. Looooong story short the initial diagnostic was a gas cap, paid for that and left the dealer. One day after getting the car back the check engine light comes on again, take it back and now they're saying i need both downstream oxygen sensors (02 sensors) and a ECU. I don't understand maybe someone can help. Is this a common issue for these cars or do you guys think I can just replace the 02 sensors and call it a day? That ECU was priced at $1050 from sewell and those oxygen sensors aren't cheap either. BTW my car is an 06 GS 300 AWD with 68k miles. any feed back would be greatly appreciated.

 

What CEL codes you are getting? Go to any natl parts store like Advance Auto, Pep Boys, etc. and get them read for free.

FWIW - rarely (if ever) does more than one O2 sensor go at a time unless there is an issue upstream fouling them both or causing both to report outside of normal operation. Yes, they do go bad but understand their 'function' is to only report when what they sense (a la sniffing the exhaust as is the case) is out of parameter. It could be bad or they could be sensing something not right (particularly since more than one tripped at once) i.e. if all 4 report fault, the issue won't be all 4 but rather something upstream like the MAF.

When multiple O2 codes are thrown, it's only a starting point as where to look for further diagnosis. Odd both of yours are post catalytic converter.

I'd start by getting all the codes read and then reporting them back here. Also check the wiring to each (melted or gnawed by rodents) and then using a multi-meter to test each of them (no need to remove - disconnect the plug). If the ECU was bad you'd likely have many more codes thrown than just those for the B1S2 and B2S2 O2 sensors.

Now, should they be bad after testing and you want to change them yourself, you can pick them up locally at a parts store (again, I wouldn't do this until you find out what codes are thrown and what the real issue is). In any event, do not get generic ones insist on either Denso or Bosch and you want them w/ plug already attached. Advance Auto also has a tool loaner program w/ 3 socket options for DIY. You buy the kit for ~ $30 and if you return it w/in 30 days you get a full refund.

Good luck

PS - w/ a 98 GS you'll have better help posting this in the 2GS forum not here in the 3GS

 

Hey, if in fact you have a 2GS, the ECU problem is usually related to dried-up capacitors. It should be all over that forum and a lot of guys do it themselves. Check over there.

 

He has a 3GS
I completely agree with BurgBoxstr. Try these recommendations first. The odds of both going back are highly unlikely. In fact, i would write teh codes down and immediately erase them and see if they return or not. Good luck

 

Yea thanks for the help guys, the car is a 2006 I tried to change my signature but I couldn't find the option.

Yea the only code it threw the other day was p0138 oxygen sensor I didn't get it checked since it came back on today ill go by advance and check it. They did mention that one of the sensors had wires taped so maybe I need to start with that one before doing both. I'm going to put it on a lift tomorrow so ill be able to tell which side that's taped if not both.

I priced the NGK sensors which seem to be significantly lower than the Denso factory ones. Do you guys recommend the NGK or should I just stick with the factory ones from Sewell? Thanks

 

LOL - sorry, thought I read that but then as I hit Submit Reply I saw the '98 in the sig and thought uh oh. I was foiled trying to be efficient...


Go w/ either Denso or Bosch and either will be fine - no need for 'factory' ones from Sewell (which BTW will just be repacked Denso).

Yeah, taped wires... that'll do it too... (thus my recommendation to get ones w/ the plug already attached).

FWIW - P0138 = B1S2 sensor... as seated in car, right side post cat sensor. Don't replace it until you know what the cause of your problem is b/c again the sensor is only reporting conditions outside of parameter not that it's bad.

Good luck

 

Quick question how can I test the 02 sensor, with the meter?? Also what is a MAF? This y pipe on my car was damaged previously so it may be in result of this but I want to make sure. If I replace the right side maybe that will fix the issue ill check into it when I get it on the lift.

Thanks

 

I would take it back to the dealer! It sounds like you have carbon buildup issues. On 2006 GS300's the engines are direct injection. With this design it is more prone to collecting carbon deposits therefore killing your o2 sensor.

The dealer is rebuilding all these engines as good faith, even if your warranty has expired or even mileage. The will rebuild the engine. Goodluck!

BTW theres a sticky on this issue

 

Yea it keeps throwing the code for the right o2 sensor... when i put the car on the lift i couldn't see the plug where it supposed to connect to the harness. does anyone know of a DIY write up for the replacement. the wires just seem to dissapear withing a hole under the car. thanks

 

I had this exact thing done, but under warranty. There is a TSB for this where they change both downstream sensors to a new type but also requires ECU replacement to accommodate the new sensor type.

Not sure why they can't just flash the old sensor, but whatever.

The TSB applies to specific occurrences of codes that signify the voltage out of the O2 sensors is not in the correct range.

 

The rear O2 sensors harnesses are behind/under the front seat beneath the carpet for the driver side, and near the center console in the passenger footwell on the passenger side.

 

Here's the static test.

 

Did you resolve it? I just got a service note from the dealer that i need 2 oxygen sensors and new ECU.

 

Just got hit with this same thing on my 2006 GS.

Is there a TSB? Not trying to pay over $2000 for this.

 

Note that O2 sensors eventually fail....if you have driven for a long time with no code, the sensor simply may have failed, both sensors are subject to a lot of heat. Note that the downstream sensor is for emissions purposes only, the primary sensor does need to be fixed or you are chugging gas...