Engine warning light!

Iceweasel

Baldytyke88 said:

facade said:

A lot of people- I'd go so far as to suggest the majority, won't do that. They either run to a garage, or believe that they can do another 20,000 miles with the warning light on, and wonder why they now need a new engine rather than just a sparkplug....

A decade ago they didn't have all these warning lights, just an oil warning light.

That's strange, as two and a half decades ago they did.

Mildly_Miffed

Baldytyke88 said:

facade said:

A lot of people- I'd go so far as to suggest the majority, won't do that. They either run to a garage, or believe that they can do another 20,000 miles with the warning light on, and wonder why they now need a new engine rather than just a sparkplug....

A decade ago they didn't have all these warning lights, just an oil warning light.

A lot longer than that!

I used to have a 1990 petrol car with an engine management light - and fault codes that could be read easily. That car is now be 34 years old.

Standardised EOBD diagnostics have been a legal requirement on all new petrol cars sold in the UK since 2001 - 23 years ago, diesel cars since 2004 - 20 years ago, and vans since 2007 - 17 years ago.

But, yes, it did used to be much harder to fault-find without the computer telling you what it thinks has gone wrong, even on the much simpler and much less efficient engines back then...

All you need for reading fault codes is a sub-five quid bluetooth dongle from ebay ( https://www.ebay.co.uk/itm/315516155524 ) and a free smartphone app (I like Scanmaster for Android), or a fifteen quid standalone device ( https://www.amazon.co.uk/dp/B07Z3HB7DR/ ).
It's that simple.

Baldytyke88

Mildly_Miffed said:

All you need for reading fault codes is a sub-five quid bluetooth dongle from ebay ( https://www.ebay.co.uk/itm/315516155524 ) and a free smartphone app (I like Scanmaster for Android), or a fifteen quid standalone device ( https://www.amazon.co.uk/dp/B07Z3HB7DR/ ).
It's that simple.

I have a Vivaro and when people say that they cannot read or clear the fault codes, they are told they need a much more expensive reader, specific to their manufacturer.

My works vehicle is running the same today, as yesterday, with faults, but it clears if I restart the engine.

Mildly_Miffed

eOBD is eOBD - it's a legally required standard.

As for fault codes - I bought a diesel Nissan from a friend. The EML was off, but there was a fault code that kept coming back for the pre-cat lambda. I changed the sensor, and I'm getting several more miles per gallon.

facade

Mildly_Miffed said:

eOBD is eOBD - it's a legally required standard.

As for fault codes - I bought a diesel Nissan from a friend. The EML was off, but there was a fault code that kept coming back for the pre-cat lambda. I changed the sensor, and I'm getting several more miles per gallon.

You will do. The pre-cat sensor controls the mixture.

The post-cat sensor checks for catalyst performance (and exhaust leaks)

Goudy

Quite often the glow plug light is also used as a fuel system warning. This goes hand in hand with the EML resetting when you turn off and back on again.

It will turn the light back on once it's detected the fault again at a specific point in the drive cycle.
The point could be something like a high fuel demand due to acceleration but the rail pressure is low due to a leak or a duff injector returning too much fuel.

Once it gets to that point, the light will come and it trips limp mode 

It's going into limp to try and protect the engine.
If it is a fuel fault,  a lean fuelling will cause a hot engine, too much air not enough fuel means red hot combustion and cause further possible damage.

It wants looking at asap as there's a possibility of further damage.

Iceweasel

Resetting it by switching off and back on again is the classic 'Head in the Sand' way of dealing with warning lights.
Someone will eventually have to pay.

Nebulous2

facade said:

WellKnownSid said:

Baldytyke88 said:

It must be a real money spinner for garages, it's almost like it's designed with that in mind.

I'm curious to know how that would work.  There is literally nothing stopping you from hooking the van up to a laptop, diagnosing the one of a thousand different reasons the light is on and fixing it.

A lot of people- I'd go so far as to suggest the majority, won't do that. They either run to a garage, or believe that they can do another 20,000 miles with the warning light on, and wonder why they now need a new engine rather than just a sparkplug....

It's easy to get out of practice or lose confidence. In my youth I swapped an engine, changed a clutch and fitted a new wiring loom in different vehicles. Nowadays with the money that is sitting in a vehicle and the complexity of the electronics I don't do very much. 

I've a van as a private vehicle, and a warning light came on. I called Renault recovery who advised it was safe to drive to the nearest Renault garage. They said a sensor on the cat had gone, swapped it out under warranty and simultaneously said they noticed one of the suspension links was worn and replaced it under warranty as well.

I think vans get better service. They have a waiting list for cars, but got me in and fixed the next day as they know most owners / drivers want to keep vans on the road. 

Arunmor

Iceweasel said:

Resetting it by switching off and back on again is the classic 'Head in the Sand' way of dealing with warning lights.
Someone will eventually have to pay.

Worth trying once or twice though before getting too excited.  But if that doesn't work then you inevitably have to do something about it.

Goudy

Mildly_Miffed said:

Baldytyke88 said:

facade said:

A lot of people- I'd go so far as to suggest the majority, won't do that. They either run to a garage, or believe that they can do another 20,000 miles with the warning light on, and wonder why they now need a new engine rather than just a sparkplug....

A decade ago they didn't have all these warning lights, just an oil warning light.

All you need for reading fault codes is a sub-five quid bluetooth dongle from ebay ( https://www.ebay.co.uk/itm/315516155524 ) and a free smartphone app (I like Scanmaster for Android), or a fifteen quid standalone device ( https://www.amazon.co.uk/dp/B07Z3HB7DR/ ).
It's that simple.

That should be able to read the generic OBD2 codes used by all manufacturers.

It will only likely read the engine/powertrain ECU though.
It won't read ABS, SRS or chassis codes.

Once you have the code/s it's not usually as simple as that.
Quite often a bit of knowledge and understanding is needed.

There are generally two sorts of sensor faults.
A broken sensor will usually be some sort of open/closed circuit related code.
It will be by all accounts there all the time as soon as the ignition it turned on as the system looks for all those sensor values.
An example is say a temp sensor is open. That part of the sensor has shorted out and a new sensor is needed.

The trick or knowledge is knowing the ECU supplies a small voltage of 5v to most sensors, the sensor than alters that voltage and returns that signal back the ECU. The ECU then knows what is happening based on the returned signal value.

The other is a sensor just reporting a problem. It's not broken or duff, something else is.
It's working fine and just seeing an irregular signal because of a fault with something else.

You might only get these faults flagged at a certain point in the drive cycle and only if the same problem is detected three times in that same drive cycle.

An example of this might be the rail pressure sensor under reporting or the IMV on the hp pump can't open enough to meet high demand, this is often a result of a fuel leak or injector leaking off too much fuel.
The sensor itself is ok but you need to know and understand what's going on to get that signal.

But the code/s are the place to start. There is always plenty posted about every code on the internet somewhere.  

As mentioned, one fault/code can cause a string of faults/codes and it can be difficult to pin point the one causing the issue and sending all the others to go off.