Check Vsc And Engine Management Liight

Lexus-IS · January 26, 2015

This morning I started up the car, it all started up fine Check Completed and everything about 30 seconds later had some random rev jumps in idle and the Check VSC and Engine Management Light came on. But this time Engine Management Light was flashing.

From previous experience I know that if the engine management light flashes with the Check VSC then it means it's a problem the car has picked up but not enough of a problem to store a code. If this happens, usually turning the car off and on gets rid of the error. So as I didnt have my code reader handy. I turned it off and on and it all went away and drove fine no problem.

My question is that now there isnt the check engine light, so I doubt it would have stored any codes for me to look at when I get home. I will have to have a look when I get home. No sure what could have caused this.

About 4 years ago I had a few occasions of the same thing happen and after about 2 years of doing that eventually I got a permanant code which was related to my transmission solenoid which I got fixed. I'm wondering if this is a symptom of another transmission issue coming up.

johnatg · January 26, 2015

In the first instance, check the Battery terminals - loose ones can give this sort of thing.

But the problem might be deeper than that!

ChumpusRex · January 26, 2015

Flashing engine management light means "serious misfire with risk of engine or catalytic converter damage", and to stop the engine as soon as safe. A solid engine light means "engine or transmission malfunction".

That said, there does seem to be a problem with the ECU software, because I've had exactly the same flashing light, check VSC with no misfiring and no codes stored. The problem happened after a cold start on a coldish, but not very cold day, when during warm-up the revs had some fluctuations.

Normally, the ECU ignores misfires for the first 30 seconds after start-up. But it seems that the fault detection can go a bit haywire, and that a temporary misfire that occurs at the instant when the ECU switches from cold-start mode to warm-up mode, can confuse the ECU and cause it to indicate a critical misfire.

Lexus-IS · January 26, 2015

Flashing engine management light means "serious misfire with risk of engine or catalytic converter damage", and to stop the engine as soon as safe. A solid engine light means "engine or transmission malfunction".

That said, there does seem to be a problem with the ECU software, because I've had exactly the same flashing light, check VSC with no misfiring and no codes stored. The problem happened after a cold start on a coldish, but not very cold day, when during warm-up the revs had some fluctuations.

Normally, the ECU ignores misfires for the first 30 seconds after start-up. But it seems that the fault detection can go a bit haywire, and that a temporary misfire that occurs at the instant when the ECU switches from cold-start mode to warm-up mode, can confuse the ECU and cause it to indicate a critical misfire.

How comes when I turn it off and on it solved the problem? I would think if it stored a code then even after restarting the code it will still show engine light because of stored codes. I've scanned for codes when i got home and no codes at all.

The problem you experienced is exactly what happened to me today, it was a cold morning but the warmest cold day we've had in a while. Usually its around 0 and minus temperatures but this morning it was 9 degrees. Started up the car and for about a minutes the revs fluctuated a little, i looked at the dash everything was ok, while getting my gloves on and tuning the audio as a got ready to set off few minutes later i then saw the dash lit like a christmas tree.

ChumpusRex · January 26, 2015

How comes when I turn it off and on it solved the problem? I would think if it stored a code then even after restarting the code it will still show engine light because of stored codes. I've scanned for codes when i got home and no codes at all.

Was the car actually misfiring? It would have been shaking and shuddering, if it was - sometimes you might notice this after about 10 seconds from a cold start, there will be a bit of juddering and the revs fluctuate.

I've checked this on mine with a diagnostic tool, and it shows that there are a few misfires, but that the ECU is ignoring them due to engine conditions.

However, a major misfire strong enough to put the flashing light on will be making the car judder quite obviously.

With mine, it wasn't actually misfiring - it just had the light on. I shut the engine off and restarted, and it was fine. When I put a diagnostic tool on, there were no codes.

This makes me think it is some kind of software bug in the ECU, which can be triggered when you get a bit of misfiring during warm-up on a cold morning when the ECU is running the normal cold-start program, but where it's not cold enough for the ECU to run the sub-zero cold-start program.

Lexus-IS · January 27, 2015

I dont know if it was misfiring or not to be honest. I always get a surge on the rev on cold start ups but not really idle fluctuation. Basically when I start it on Cold the revs start off at certain rpm then gradually drop to just under 1k rpm but it's like the car then realises "oh thats too low" and it shoots back up to where it started at and stays steadily there. It only does this the once. I havent had any shaking or shuddering in a long time. The last time I had this was years ago when I had transmission problem but once transmission ECU was updated I havent had shuddering issues at all.

Lexus-IS · January 28, 2015

How can misfire tests be performed? I have a OBD tool and use dashcommand app, which seems to have extra functions and features. Not sure if misfire tests can be performed with OBD. Wondering if it's worth having misfire tests carried out at the dealers?