Cat overheat warning light

Just seeing if anyone has had this problem with there cars, just starting happening on my skyline, took out for drive the other night no traffic or anything so gave her a good spirited drive but a few days later this light appears on the dash and the car keeps stalling, turn the key off and on and she starts up again straight away??

Changed the spark plugs, and fuel filter, cleaned both Mafs and ordered 2 O2 sensors

Also I've noticed when she's playing up the water temp goes from 80 down to 65-75, as I've got aftermarket temp gauge which reads precise...

Any ideas would be greatly appreciated

interesting .
Couple ideas could be bad electrics, bad earth/power voltage drop causing issues or an actual running condition that is actually getting egt high .
As far as I remember on the the oem cat egt is much like the gtir and just a basic high temp switched warning light with no logic beyond that .
Aftermarket ecu can utilise it for other warning status .
If actual running condition is getting hot fuelling ratio and cat flow (if fitted) needs looking at .

under what conditions does it stall ?
does it only happen after driven hard and how quick does water temp drop (gradual or sudden change ?
Is ecu standard ?
Does it have cats fitted and cat egt actually fitted/plugged in ?
have you had any other odd electrical type gremlins ?

Hi Mr B

Car plays up after 2 minutes stone cold or 30 minutes or driving

Sometimes water temp never gets to 80 degrees always around 70 degrees

Also ecu I'm unsure but I've got power fc commander fitted, and I'm thinking the light is connected to commander as warning for something major

No other gremlins tbf just fluctuating water temp, also worth mentioning when car does stall, it fires up straight away when you turn the key, so I'm thinking electrical fault and car is in limp mode

Yes on apexi system many set up that light for warning knock or injector duty
I would be checking knock sensor and fuelling ratio and coolant system thermostat control perhaps
Safe mode/power cut running could account for lowering temps too .
looking through pfc may highlight exact reason it triggering the dash light and help give direction for areas to diagnose pending on settings and values you review .

Ok thanks will hand a look later in the week what it's saying, could it be thermostat playing up which is giving the water temp issues?

Possible and worth looking at if other investigations are fruitless .
Does seem likely from remarks so far main issue going be wiring or electrical component related but ruling out all basics can be helpful, is also possible have more than 1 issue that interact together .
On older cars I found it useful check lot of basics as 20yr old parts or poor quality/wrong part replacements often found be an issue .

Yes I agree, I try and only buy genuine parts now especially if there electrical

Low voltage causes the cat light on many Jap cars it could also cause temp error and other issues -
Check alternator output and voltage at fuse box

ADSgtir wrote:Low voltage causes the cat light on many Jap cars it could also cause temp error and other issues -
Check alternator output and voltage at fuse box

Ok thanks will do

1st pic cold idle



Second pic 10 min blast

Car temp stayed on 73-73C cat warning light didn't come on

you looked through the controller menu to see what the cat light setup and triggers might be ?

Not yet don't want to bugger around with it to much, need a user manual or summit

It is possible the Apexi unit is using the CAT light as an EML warning light , I don’t know how it’s configured, but as a normal config without Apexi the CAT light is either blocked cat causing high temp or far more commonly- low voltage causing a false overtemp warning .

On the Apexi standard dash eml light is utilised.
In the menu other modes - etc - function select you can set the cat warning dash light to function as knock or injector warning function or even air flow sensor or O2 sensor I believe .
I've dealt with some and knock warning seem favourite but some like injector warning pending how hard the duty being push .
The other initial question is do you have cats and/or the temp sensor still physically fitted .
If I was diagnosing it first thing I do is quick visual checks see if got the sensor fitted and a look at the power fc etc menu see what setting it currently using .
Even if temp sensor present you would want manually jump it to see if still functional input as many times they just fitted for sake of being a bung .
Apexi not nicest work with for diagnosing faults but your fault seems likely easy one narrow down to power or grounds or an actual true sensor value triggering it .

Don't you just love old Nissans, who needs hobbies lol

Parameter table, knock is at 20 on 3k revs

Mr B I have Sard Cat fitted with o2 sensor, and both temp sensors still fitted

ADSgtir wrote:It is possible the Apexi unit is using the CAT light as an EML warning light , I don’t know how it’s configured, but as a normal config without Apexi the CAT light is either blocked cat causing high temp or far more commonly- low voltage causing a false overtemp warning .

When first stalling and cat light on, cat is not red hot same temp as exhaust as I felt it with the back of my hand

All sensors seem normal unless I'm wrong?? Just noticed as I was revving th engine the FC commander was dimming slightly, so whether the alternator is playing up but it's reading 14volts?

Sorry for loads of replies but page keeps refreshing when writing a post

old NISSAN is the good life :-)
much more logical engineering than most euro junk of similar era.

If you lucky it be a main ground or power fretted/corroded .
And if luck continues it be visually noticeable  .
you could also try running additional electric loads and see if helps trigger the issues .
checking alternator ac ripple and testing full load amp output and regulated voltage would be quick way get an idea on alternator health

Try and look in the etc menu and see if and selections been made for warning lights so you know the operation and can evaluate all possibilities accurately .

Thanks Mr B, will have a good look on Saturday

So found out how to see what warnings are programmed and it looks like in Japanese that the 02 sensors are set to warn the driver and knock and injector are turned off