Obd Codes

[sean_co]

Good evening,

i was the one that started the topic http://www.lexusownersclub.co.uk/forum/topic/96535-exhaust-changes/. since it has moved from actual exhaust changes to trouble codes, i though i would start a new topic.

been having CEL lights come and go, the last one in fact went away by itself. started up the car and code was gone. decided to get a BT ELM scanner and the torque pro app. past day or so things were fine. tonight i stopped at home and scanned for any faults and found P0171 and P0174 thats Bank 1 and 2 system too lean apparently. those codes are listed under pending fault and no CEL on the dash. I believe the ECU randomly sets a rich or lean condition to test the cats which have been removed in this case. would these errors be related to that or should i be logging other info / sensors to get a bigger picture of what could be wrong?

been watching the short and long term trim levels and both short terms (bank 1 + 2) are between -7% and +7% depending how i drive but both long term trims are on +30% (seems a bit high)

[Peter P18]

Hi Sean.

I actually posted for an update on your old thread! ;)

Then stumbled across this one!

I'm still not convinced this is related to the removal of your secondary cats.

No one on the US side has had any issues with CEL's or faults when they have removed theirs.

If it was me, I would be more interested in the O2 sensors (4 in total).

May be worthwhile replacing them to see if that fixes the issues?

I'm guessing you've also check your AFM to make sure that isn't gunked up etc?

The symptoms you are experiencing just don't tie up with removing the secondary cats mate.

As I think you already know, there is zero monitoring of the secondary cats. It's the primary's that are monitored by the O2 sensors.

That's one of the reasons you see guys fitting O2 conditioners when they replace the headers.

Do you know what grade of octane your fuel is by the way? We are quite lucky over here in the UK, and can easily source 98 or 99 RON.

You don't have any induction kit or aftermarket air filter do you??

[sean_co]

Hi Sean.

I actually posted for an update on your old thread! ;)

Then stumbled across this one!

I'm still not convinced this is related to the removal of your secondary cats.

No one on the US side has had any issues with CEL's or faults when they have removed theirs.

If it was me, I would be more interested in the O2 sensors (4 in total).

May be worthwhile replacing them to see if that fixes the issues?

I'm guessing you've also check your AFM to make sure that isn't gunked up etc?

The symptoms you are experiencing just don't tie up with removing the secondary cats mate.

As I think you already know, there is zero monitoring of the secondary cats. It's the primary's that are monitored by the O2 sensors.

That's one of the reasons you see guys fitting O2 conditioners when they replace the headers.

Do you know what grade of octane your fuel is by the way? We are quite lucky over here in the UK, and can easily source 98 or 99 RON.

You don't have any induction kit or aftermarket air filter do you??

i agree with you, i think its something else other then the cats.

with the OBD adaptor i checked the fuel trims and the short terms were fairly low but the long terms were +30%. started poking around and found a seriously dirty air filter and the mass air flow was all dirty. i replaced the filter and cleaned the MAF and the fuel trims have come down to a much better level. short term is around 2% and long term at idle is 0%. by the looks of things that must have sorted out the bank 1 and 2 lean error codes.

as you say, if i get a CEL light again i will check the codes, most probably going to be a faulty / slow sensor.

although now i do have a pending P0420 (catalyst system -efficiency below threshold), not sure if that will set a CEL over time?

in south africa where i stay we can only get 95 fuel and at the coast i think we can get 98.

no induction kit at this point in time, might be something to consider down the line once all the errors have been sorted.

[ColinBarber]

P0171 and P0174 are errors from the upstream sensors, before the cats so this doesn't have anything to do with the cats or back part of the exhaust. Given that both banks are producing an error it also really eliminates the sensors as well (unless they have both been damaged). You need to look at something common to both banks, mainly on the induction side of the engine after to MAF, or the MAF itself. Try cleaning the MAF, if you have an oiled air filter the MAF sensor wire could be coated in oil which will affect the fueling.

Normally the ECU will use the sensor data and look up table to provide the correct fueling. The O2 sensors are then used as a closed-loop system to correct any error. You are way outside of normal operation, the long term trim are right over and the ECU has had enough and triggered the CEL.

As these are engine too rich errors I wouldn't have thought the problem is an air leak in the induction - you would expect it to be too lean. One possibility to too high a fuel pressure which would affect all cylinders, or clogged air filter.

[sean_co]

Just a quick update. the air filter was replaced and air flow meter was cleaned (MAF). no longer getting lean errors which is great. fuel trims are very close to 0% most of the time now, both short and long terms.

below is a screen print of the errors now. these are pending but they do set a fault after driving a few KMs'. i reset them and after some time they came back. as mentioned many times before these cars are ok with secondary decat, can this then be because of 2x faulty O2 sensors. should i be looking at the primary cat / O2 or the secondary cat (removed) / O2 with errors like this?

better yet, what can i log to see which sensor is giving this error? i might try adding the "mini cats" back in just to see what effect it has on this error if any.

[Peter P18]

Based on Colin's post above, looks like the error codes relate to the upstream O2 sensors. That's where I would start I think.

I'd avoid re-installing the mini-cat's if I was you. May well have something to do with why the O2 sensors went wrong to begin with!

With your car as the only notable exception, I have NEVER seen another ISF with mini cats like those!

Get yourself a pair of upstream O2 sensors and see if that fixes things for good.

Best of luck Sean. :)

[sean_co]

Based on Colin's post above, looks like the error codes relate to the upstream O2 sensors. That's where I would start I think.

I'd avoid re-installing the mini-cat's if I was you. May well have something to do with why the O2 sensors went wrong to begin with!

With your car as the only notable exception, I have NEVER seen another ISF with mini cats like those!

Get yourself a pair of upstream O2 sensors and see if that fixes things for good.

Best of luck Sean. :)

defiantly need the luck with this project. :)

will see if i can get 2x primary O2's in the next couple of days. from under the car i was able to see the primary ones, how difficult is it to remove them?

also if the primaries are faulty, would that not be messing with my Air fuel ratio?

[Peter P18]

You'd be best off getting the car up on a ramp to make removal easier. A lot of the guys in the States buy replacements when they change out the headers for Novel, PPE or SIKKY versions. Reason being the original items can be tricky to remove without damaging them.

I'd get some WD40 or similar penetrating fluid on them for as long as possible beforehand. Just let them soak for a while.

AFR would not necessarily be affected by faulty O2 sensors. The AFR relates to the intake side of the combustion process, the O2 sensors are monitoring the spent gases from the exhaust end of things.

Hope you get things figured out soon Sean. :)

[sean_co]

You'd be best off getting the car up on a ramp to make removal easier. A lot of the guys in the States buy replacements when they change out the headers for Novel, PPE or SIKKY versions. Reason being the original items can be tricky to remove without damaging them.

I'd get some WD40 or similar penetrating fluid on them for as long as possible beforehand. Just let them soak for a while.

AFR would not necessarily be affected by faulty O2 sensors. The AFR relates to the intake side of the combustion process, the O2 sensors are monitoring the spent gases from the exhaust end of things.

Hope you get things figured out soon Sean. :)

perhaps while im at it, might be a good idea just to do all 4 of them if the price is fair? for a minute lets assume all my O2 sensors are working. would this error then mean the primary (upstream) cats are faulty?

[Peter P18]

I'd probably do the upstream ones first unless you can get a good deal on all four.

If that doesn't solve your issues, next thing would be the cats. :(

You may want to consider adding an O2 conditioner from the likes of PPE or SIKKY first though?

Just a thought.

[ColinBarber]

perhaps while im at it, might be a good idea just to do all 4 of them if the price is fair? for a minute lets assume all my O2 sensors are working. would this error then mean the primary (upstream) cats are faulty?

If we assume all the sensors are ok then you have a leak in the exhaust or the cats aren't working correctly. The new errors P0420 and P0430 are produced by the downstream sensors, ones located after the cats which crudely try and determine if the cats are working well.

There are typically three reasons that produce this fault:

1. The upstream sensors are faulty which means the oxygen levels in the exhaust gases are different to what the downstream sensors expect to detect (hard to believe that both banks would have the same fault)
2. If you have a hole in the exhaust then it will affect the amount of oxygen the sensor detects and so trigger an error. (again hard to believe both exhaust systems would have the same issue)
3. The cats aren't working correctly

It is rare that a downstream sensor itself is faulty which triggers this fault, and again you wouldn't have both with the same issue.

If you have removed cats and the rear sensors are downstream of those cats then it is correctly detecting an inefficiency - this is when you use simulators to fool the ECU into thinking the readings from the downstream sensors are correct.

[Peter P18]

Any updates Sean??

[sean_co]

Any updates Sean??

no new updates as yet. im trying to find someone with an IR thermometer. just want to check temps at the front of the cat vs temps at the back of the cat. that will give an indication of the cat condition.

also before i replace anything i would like to check wiring from the 4 sensors just to make sure no one has tried to do something there. i did find one suspicious looking wire just loose in the engine bay, makes me wonder. i did dig a bit deeper into the diagnostic software and i found what looks like a slow O2 sensor warning so im leaning towards replacing them.

but for now i just keep checking the error codes to make sure its nothing new. should have some time this weekend to poke around some more.

[sean_co]

Any updates Sean??

today i managed to get off of work early and went through to an exhaust place. ironically they recognised the car as they were the ones that cut out the secondary cats. i wanted to check the primary cats so we put the car on the lifts and removed the exhaust from the primary cats. turns out they have been emptied out. its no wonder i keep getting the CEL, i am essentially running a cat less system. but looking at the car you would think the cats are there.

long story short i have received my O2 conditioner and tomorrow morning i will be installing it. litle bit of wiring involved in some tricky spots by im sure this will clear the CEL for good.

this is the start of the install, will post some more as there is progress tomorrow. will probably solder each connection just for good measure too, dont want intermittent connection issues

[sean_co]

just 2 photos during the install. this was probably the most difficult wire to get to. on the ECU it is in port E3 28 which is right at the back, so the easiest way to get there was to disconnect the Battery and unplug all cables. This brown wire and the switched power black/Red on port A6 2 were the only ones that i used electrical tape on as they were not cut, there were also soldered though.

the rest of the joins were cut, soldered and heat shrinked. So far so good. went for a test drive and the DCT tests all passed. that includes O2 sensors and catalyst checks. no CEL currently and also no pending codes :hocus-pokus: .

[JonP]

Very well done sorting that out, good job!!

[Peter P18]

Glad you are getting to the bottom of your issues now Sean.

I did wonder if the primary cat's had been gutted. Would certainly explain why you were having the O2 issues!

Let us know how you get on with your O2 conditioner. Should solve the problem based on what the US guys have said. :)

Hopefully you will be having many trouble-free miles of enjoyment soon!

Cheers.

[sean_co]

the O2 conditioner is working wonders. no more Cat error codes. infact no more issues / codes at all until today, i think i caused it though.

i had the conditioner mounted outside of the ECU box, didnt look like it was going to fit properly. noticed it was getting fairly hot. no real airflow where i had it mounted. so today i moved it into the ECU box. tight fit but you can get it in there and its now running cooler then before. looks like there is an air vent into the ECU box.

during the conditioner relocate i had the negative Battery terminal off, just incase. was probably off for about 20 min. i noticed the first start after that the engine ran for about 3 sec and stopped, restarted and all was fine again except i got the VCS light after a few km. also noticed the reverse camera was saying initialising. went home and removed the negative terminal again for 5 - 10 min.

on first start again it ran for about 3 sec and stopped, restarted and all was fine. camera did the same again so took a chance and turned the wheels full lock left and full lock right. as i did that the camera came right. am i starting the engine too soon after reconnecting the Battery? seems like im starting it while its calibrating something or doing initial checks. no VCS light after this round, hopefully it wont come back.

seems to be very fussy when batteries are disconnected. did a similar thing when i put a new Battery in the car.

[Peter P18]

Odd....

The failing to run after you re-connect the Battery is normal. It always cuts out the first time you try starting it. Second time works fine.

The nav unit will initiate and download for a while.

Never noticed the reverse camera not operate?

All I can tell you is you don't need much to be wrong for the check engine light, VSC to throw a fit!

I had the wires reversed on a throttle controller install once, and it went into limp home mode, check engine light, VSC etc.

Even when I connected them correctly, it was still flipping out.

Only solution was to dis-connect and re-connect the Battery.

Just make sure all your connections and wiring for the O2 conditioner are correct.

Not fitted one myself, but the U.S. forum should have plenty of info if needed.

Hope you get it sorted mate. :)

[sean_co]

Odd....

The failing to run after you re-connect the battery is normal. It always cuts out the first time you try starting it. Second time works fine.

The nav unit will initiate and download for a while.

Never noticed the reverse camera not operate?

All I can tell you is you don't need much to be wrong for the check engine light, VSC to throw a fit!

I had the wires reversed on a throttle controller install once, and it went into limp home mode, check engine light, VSC etc.

Even when I connected them correctly, it was still flipping out.

Only solution was to dis-connect and re-connect the battery.

Just make sure all your connections and wiring for the O2 conditioner are correct.

Not fitted one myself, but the U.S. forum should have plenty of info if needed.

Hope you get it sorted mate. :)

nice quick reply :)

well the camera was working but when i turned the steering wheel there were no guidance lines as normal. once i did the full left and right locks they came back as usual. very strange.

so far things are ok again after the second reset, if it comes back tomorrow i will check the O2 cables. that should be ok though cause my scanner shows the O2 sensor passed and the CATs. haha, they passing now but dont even exist, O2 conditioner for the win :)

been reading about zero point calibration, its resetting the steering wheel angle so the traction control knows whats happening. found it here http://www.lexusownersclub.co.uk/forum/topic/83148-gs300-2002-vsc-vsc-lights-on/ post number #3. would these pins be the same on the IS-F? perhaps after power loss the angles are set? i dont know there is so much electronic stuff going on in these cars

[Peter P18]

The O2 conditioner is a very clever device from what I can tell. :)

Glad to hear it's working for you chap.

I'm not sure on the pins mate. I doubt it would be anything to do with that though? I have never had any issues with VSC after dis-connecting the Battery.

The failure to start on the first try after re-installing the Battery is 100% normal though. :)

Fingers crossed it keeps on working fine for you.

Keep us posted.