Ls400 'check Engine' Light On!

[NormLS400]

Hi

My 'check engine' light came on in my mk4 LS400 yesterday, along with a loss of power, which I assume may be some sort of limp home mode?

Anyway, my local garage cannot get it connected to its diagnostics so I've got it booked in to the Lexus dealer tomorrow to have it checked. From what I've read it sounds likely that it might be an oxygen sensor? Is that possible?

If so, I gather they are quite expensive from Lexus. Is getting an after-market one a possibly? I see Denso make them? Does anyone have experience of these, and is it going to be easy enough to just buy one and get my local garage to fit it? (much cheaper than dealership hourly rates!)

Thanks

[LowriderUK]

O2 [lambda] sensors are screwed the device that screw into the exhausts, so it's not any challenge for any competant mechanic to change them.

The LS400 [all models] had both pre-cat and post-cat O2 sensors, so finding out which ones are faulty is important if your going to replace them with OEM parts.

You can use a universal O2 sensor instead of a genuine part, but it will require the original plug from your existing sensor cutting off and soldering onto the univeral one. Again, not a hard job.

Here's a guide for the UCF10 as an insight into what is required. It's pretty much the same, from what I can tell, for a UCF20 [Mk3/4].

http://www.lexls.com...ygensensor.html

http://www.lexls.com...ygensensor.html

[NormLS400]

Thanks lowrider. I guess finding a sensor that's a straight replacement would be ideal, if the difference in cost is not too much.

My local mechanic said his diagnostics machine wouldn't connect to the car, and he doesn't know why. I hope the Lexus dealer can get a reading tomorrow... and ideally within the 1 labour hour timeframe!

I've got to drive about 1 hour to get to the dealership tomorrow, so I hope I make it there ok. Not sure if it's actually in a limp home mode, but it feels like it. Also sort of stutters / misses a little when driving up a hill or something. However, when it's cold it drives perfectly fine for the first few minutes until warm and then the check engine light comes on and that loss of power / etc.

[steve2006]

Please come back when you have the diagnosis and let us all know the result, surprised a garage specification OBDII reader wouldn't connect,I heard of some cheap DIY ones that don't.

[NormLS400]

Please come back when you have the diagnosis and let us all know the result, surprised a garage specification OBDII reader wouldn't connect,I heard of some cheap DIY ones that don't.

Hi, yes it's strange. He said they actually have quite an expensive machine and a small hand held one as well, and neither worked. I will post again this afternoon when I'm back from the dealership.

Thanks

Norm

[Manc]

if its stutters it could be your jets are blocked.... look for the info on the Throttle Body.... i already had my engine light on when this happened to me, the light was for the EGR pipe blowing - readout gives 3 codes... but its just a blowing pipe!!!

A stutter sounds like a blockage of some sort... i wouldn't have thought the engine would do strange things after a O2 sensor goes... they are way after the engine....

can you not wire up the obd to get the codes? on the OBD version 1, you just loop a wire from 2 of the connectors & the warning light then displays the code... really easy to DIY.. can this be done on OBD2 anyone?

[NormLS400]

So I'm back from the dealership and they got the error codes which were P0135 and P0325. Cost me £180! They say this is the oxygen sensor, bank 1, passenger side. Am I correct is say this is the pre-cat one, i.e. the one closer the front of the car?

£202.72 +VAT for the part alone from Lexus, so ideally I can find an OEM pattern part for cheaper somewhere and just get my garage to fit it.

[NormLS400]

I managed to get a sensor ordered from a place called worldcarparts.co.uk which I saw another club member had recommended, as he had a similar problem on his LS430. Only cost £77.58 inc. delivery, so hopefully that will be it!

I have to say that I think the dealership charging me £180 just to get the codes is a bit much. I think they are shooting themselves in the foot a bit because I would only ever go back if I absolutely had no other option.

[steve2006]

How long did it take to plug in a code reader and retrive the codes! I assume for £180.00 you got a full valet and a full tank of fuel!

Codes look strange I think it should be

P1135

Air/Fuel Ratio Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

[NormLS400]

How long did it take to plug in a code reader and retrive the codes! I assume for £180.00 you got a full valet and a full tank of fuel!

Hi, I think the charge was 1 1/2 hours. They also did an overall vehicle check, which is fine, but I didn't ask for that. They did offer to clean it but I didn't have any more time to wait on that.

[steve2006]

The code suggests it is the pre cat sensor so the one nearest the engine, it may be worth having your garage check the wiring before replacing the sensor as the loom is exposed and subject to temperature extremes.

The other code is

P1325

Igniter Circuit Malfunction (No. 6)

Which I think is a result of the faulty O2 sensor throwing a misfire code I hope it's not just a spark plug or coil pack!

[willskoda]

Sorry - off topic - but can someone tell me where the OBD port is located in the 400?

[NormLS400]

The code suggests it is the pre cat sensor so the one nearest the engine, it may be worth having your garage check the wiring before replacing the sensor as the loom is exposed and subject to temperature extremes.

The other code is

P1325

Igniter Circuit Malfunction (No. 6)

Which I think is a result of the faulty O2 sensor throwing a misfire code I hope it's not just a spark plug or coil pack!

Interesting thought about the spark plug. I don't have a record of when they were last changed actually. Fairly expensive for the LS400 I gather?

Anyway, the oxygen sensor should arrive on Monday so I'll get the garage to install it on Tuesday and I'll report back.

[NormLS400]

The code suggests it is the pre cat sensor so the one nearest the engine, it may be worth having your garage check the wiring before replacing the sensor as the loom is exposed and subject to temperature extremes.

The other code is

P1325

Igniter Circuit Malfunction (No. 6)

Which I think is a result of the faulty O2 sensor throwing a misfire code I hope it's not just a spark plug or coil pack!

Interesting thought about the spark plug. I don't have a record of when they were last changed actually. Fairly expensive for the LS400 I gather?

Anyway, the oxygen sensor should arrive on Monday so I'll get the garage to install it on Tuesday and I'll report back.

[steve2006]

Sorry - off topic - but can someone tell me where the OBD port is located in the 400?

It should be located under the driver's side kick panel, look underneath where the parking brake release is then move towards the drivers door side, it should have a little pull down cover over it.

[willskoda]

I had a look today - I have a round hole that says "diagnostics" on it - Obviously not OBDII

[NormLS400]

So the latest is that my local garage fitted the new oxygen sensor but the check engine light still comes on. They cannot clear the codes of course because they still can't get the diagnostics reader to connect with the car. They tried disconnecting the Battery for a while but it still comes on.

They say the car runs fine now though, but I'll check when I pick it up tonight.

Could the problem be that I need to get the error code removed... from the dealership? When I called the dealership in Edinburgh this morning about it and they said they might not remove the code as I didn't get the work done there. They were going to check with the foreman and get back to me but still no call! Talk about poor service!

I wonder if it might be worth trying to find another independant local garage with an OBD2 reader to try that. My guy cannot understand why his won't connect with the car.

Very frustrating stuff!!

UPDATE - Lexus Edinburgh did finally call me back. They said it will be at least another labour hour to reset / remove the error code. And even then they didn't sound sure that would solve the problem. Obviously not keen on the fact that I bought a sensor elsewhere and had another garage fit it, which is sort of understandable, but to charge that amount of money for something that should only take seconds is way too much IMO.

UPDATE - I picked it up but it still isn't running right! Aaaahhhh!!!

[NormLS400]

Just a quick update on my problem. I was obviously at a bit of a loss with this, so I decided to take the car to a small independent garage in Glasgow (over 2 hours drive from me!) as I know the mechanic there relatively well and he specialises in more unusual cars. He managed to get a diagnostics reading and the only remaining code was for the knock sensor, so I decided to get both of those replaced. When he took the manifolds off he found some sort of animal had tried to make a home on the middle of the V, and chewed through the wire to the knock sensor!! Anyway, he sorted the wiring, fitted 2 new knock sensors and it's good as new!

Lesson learned though.... I'll not be going back to a Lexus dealership again!

Anyway, if anyone lives around the Glasgow area and is looking for a competent garage, I'm happy to pass this garage owners details on, just email me nvk280 at hotmail dot com

[cruisermark]

Glad you got it sorted after so much hassle trying to pinpoint the problem