Hi All,

Today, whilst driving on a particularly rough stretch of road (which is typical of these parts as BigBoomer will attest to), I had three warnings come up simulataneously - Check VSC, 'Check Engine' and TRC OFF.

I checked - and cleared - the error code which was P0031 (see picture). And on restarting the car, the warning lights did not return. (So on that basis the error code pertaining to the O2 sensor was not just a red herring!)

Now. Please could somebody explain to me, like I'm five, how an O2 sensor anomaly could have anything to do with VSC or traction control? (I mean, I get that driving on bad pavement could knock something out of whack. But an O2 sensor?) More bizarrely, I've seen posts that talk of a leaky fuel filler cap causing the same thing!

Cheers guys...

 

From my brief experience and readings, it seems Check VSC is added to every Check Engine code. For example: O2 sensor, EVAP system, or VVTi Solenoid issues.

If there is no code, VSC OFF is indicated due to bad fuel cap or when yaw calibration is required, and maybe other issues. It seems yaw calibration is affected when we clear engine code(s) using OBD-II scanners.

I assume VSC OFF and TRAC OFF indicators are related.

I hope mechanics and other more experienced DIY owners will educate us.

 

To the OP. What year is your LS430.? Yes it’s true that the all those lights you are referring to will illuminate when there is a trouble code. Clearing the DTC will not necessarily clear the lights until the problem is fixed. . Sometimes they still don’t go out even when issue is repaired In that case and only if u have an 01/03 the paper clip fix will work. Won’t work with 04-06. Look up paper clip on the LS 430 forum for details. Good luck

 

Thanks - I saw that fix, but having cleared it with the scanner, it appears good for the moment.

It's an '04, by the way. The only other time I had a warning was on the drive home from having bought the car - when I got the dreaded 'Low Tire' alert. (Pressures were OK of course, I reset it under the dash and it hasn't occurred since.)

Just seemed like more than a coincidence that it happened when driving on a road with a lot of patchwork.

 

Potholes, yup we have them everywhere, lots of them, big ones, small ones, everything from minor cracks to axle-breakers. It comes from 13 years of "Austerity" which is Tory for "we stole that money".

Chances are that the jolting from the potholes caused one of the connections on Bank1 Sensor1 O2 sensor to momentarily go high resistance so the voltage at the heater coil is too low.
That is enough to trigger the code. Since it went away with the reset it is working normally now.
However, that doesn't mean it won't come back, and it may be a first indication of a failing O2 sensor or a broken wire/connector.

As for the Check VSC & Trac Off, I had the same when my Bank2 Sensor 1 heater failed. What is really insane is that these heaters are ONLY for when the engine is cold. Once up to temperature the engine keeps the sensor hot enough.
The emissions that a failed O2 sensor heater can cause is limited to a minute or so after a cold start, but it can cause clogging/fouling of the CAT, so best to swap it out as soon as possible.
I have absolutely no idea why the Traction control or VSC are disabled as they are safety systems and should be able to cope with a failed emissions/engine tuning sensor.
Disabling those in any situation that does not 100% require it is dangerous and stupid.

 

Mine LS430/2006 got exactly the same errors today. I left the car off for 4 hrs then errors were just gone!

Can anyone shed some lights on this please?

 

Right. Today I did the same journey as per my original post. And guess what? In almost exactly the same location, i.e. downhill on a certain heavily-patched road - BING - I got the 'Check VSC' and 'TRC OFF' exactly as before.

So now I'm thinking: Was the O2 sensor code unrelated after all, but clearing codes just happens to reset various warnings also? Perhaps a downhill stretch of rough surface really is enough to trigger the VSC warning! (In which case this car is not fit for purpose in this country of third-world roads!)

By the way, this car, on it's 18" wheels, must surely be the roughest-riding vehicle I've ever had.

 

Have you checked what code is thrown this time? If the code is different it might be that there is a powerful radio transmitter on that road that is false-triggering the fault. What exact road is it? Maybe I could drive down it in mine and see what happens.
If the same code as last time, then I would recommend changing that O2 sensor.

As to the suspension, if yours is the worst riding car you've ever owned, there is either something serious wrong or else the other cars you've owned were all amazing.
My LS430 is wafty and the smoothest I have ever owned. Way better than my Honda Legends (1998) and my 2001 S-Class.

 

Hi BB,

Not checked the code as yet. The location is just about here, towards the bottom of the hill, heading west. You probably know it. (Yes there is a water pumping station on the left, a bit further back. Interesting thought!)


I'd like for you to ride in my car. (And vice-versa?) I say 'rough', but actually much like just about every other car these days. Impossible to compare with a 400 on 15 or 16" rims, with conventional springs. (Chris at Westfield said it drove 'nice', and concurs that people do comment that the ride of these cars is not in the same league as a 400.) What I will say however, is that selecting sport mode on the suspension does not make the slightest bit of difference that I can perceive!

Thanks,

R

 

I know it well. I used to live in Hullbridge. Could be the water pumping station or something else in the same area. There used to be a taxi company radio transmitter there on the corner of Lower Road and Hillcrest Ave.
If you want to test on a REALLY bumpy road, drive down Ferry Road and turn left onto The Drive. If you can do 30 along The Drive and not get an error, then it is definitely nothing to do with the O2 sensors.

The 400 has a more wafty ride but if you start throwing it around a bit, then it leans and wallows and really struggles.
If by ride you mean isolation from the road, then the 430 does not do that as well as the 400.
If you want that isolated, soft ride, then you need a 400 or a Rolls Royce, or a Citroen CX.

The 430 with the air-suspension deliberately firms up over rough roads or if you are throwing it into corners, because it reacts to how it is being used.
My "Sport" button does make a difference but you need to be driving it HARD to notice the difference.
I only really noticed the difference when I got to hoon around a race track for a few laps.

 

After sitting idle for a few days, the condition had not cleared itself (see above). Codes cleared, all looked good. Drove over some rough paving (in a different location this time) and BING - same warning lights and code (P0031).

I now have it booked in to get sorted.

I hope 'Bank 1, Sensor 1' is not the one where they have to take the carpet up to get at the connector! (I already have the creases in the carpet where it was done at some point before.)

I wonder if this could also explain my really bad m.p.g. - around 19 [English gallon]. (My '98 LS400 returned around 24, typically.)

 

Bank 1 Sensor 1 is the left side of the engine before the CAT so no need to lift the carpet.
It may help the Mpg but not likely. Mine is currently averaging 21Mpg because it's all local trips.
Once I get her on the motorway at a constant 70-ish it soon climbs to the mid 20s and on longer runs into the high 20s.

 

Yes it was the O2 sensor.
Yes it was expensive.

 

Yay! :-)
Oh dear. Mine cost me about £200 including fitting but it was the right side (Bank 2 Sensor 1).

 

Well you can double that - although this did include a 'diagnostic charge' which I thought was a bit cheeky. (Mind you, I have been known to misdiagnose, so I don't really have a strong argument!)