Engine Management fault

[Mick Howes]

After more than 3 years without a single glitch with my 95 LT1, today my engine management warning came on. No loss of power, in fact nothing of note except for the fan coming on. Another odd one, when I got home, reversing into my parking space, the warning went off, as did the fan, but when I shifted back to Park, lamp came back on along with the fan. After leaving the car for an hour, started up, no fault indication, but it did come back after around 5 miles, exactly the same as described before. Any ideas?

 

[teamzr1]

Hi Mick
I would first test the battery as when it is low or has a bad cell the electronics do weird things
If not having a battery load tester do you know someone who does or maybe an auto parts store could

Check the battery cables to battery, are the posts clean and the cables on tight
With check the key on but engine off what is the voltage read at battery posts and then showing on the voltage gauge
Voltage should be around 12.5 volts

Then read again when engine is at idle
Make sure the alternator is outputting OK
Voltage should be around 14.5 volts

Being you have a 1995 C4, that is OBD-II, not OBD-I so if having a code scanner or again at auto parts store
see if and what error codes (DTCS) are and report that

If having or obtaining a OBD-II scanner would allow driving and the scanner recording engine and any DTCs would help
point to what the problems maybe

I assume you mean the coolant fan ?
What is the temp reported on the gauge on the dash ?

 

[Mick Howes]

Definitely not the battery, and my car is used every day. Going to book into my local garage that works on US cars, they do all my servicing and MOTs. Hoping it's just some strange, easily rectified, glitch, as I said, no power loss or misfire, the usual problems when engine management fault comes on.

 

[Mick Howes]

Meant to add, coolant temp normal, level correct, as is oil.

 

[teamzr1]

You need to see when the fan comes on
if the temp gauge reading jumps on or still shows normal (I assume around 200 F deg)
If the temp jumps up, could be the wiring or connector to the coolant temp sensor off the block
or the wiring pins for ECT sensor at the PCM which sits on drivers side of firewall at the top
or maybe the wiring connectors to PCM got loose, not fully plugged in

Could at idle is wiggle the wires at the ECT and see if fan comes on, do same at the PCM
Check for any loose or dirty ground connections to engine block and PCM

You mentioned "engine management warning came on"
Was it the service engine soon, or the check engine light that came on ?

 

[Oneball]

You need to get the code read. A lot of cars will kick the fan on permanently as safety feature when an error is registered, it’s part of limp mode. Can’t say for certain if a C4 does but it’s not uncommon

 

[Mick Howes]

You need to see when the fan comes on
if the temp gauge reading jumps on or still shows normal (I assume around 200 F deg)
If the temp jumps up, could be the wiring or connector to the coolant temp sensor off the block
or the wiring pins for ECT sensor at the PCM which sits on drivers side of firewall at the top
or maybe the wiring connectors to PCM got loose, not fully plugged in

Could at idle is wiggle the wires at the ECT and see if fan comes on, do same at the PCM
Check for any loose or dirty ground connections to engine block and PCM

You mentioned "engine management warning came on"
Was it the service engine soon, or the check engine light that came on ?

It was the SES warning

 

[teamzr1]

Service Engine Soon, refer to your owner's manual, page 2-80
That is to say, something needs to be serviced and reason car drives just fine
That tells you such as change oil, air filter, coolant, fuel filter, etc

As to fan unless you check what I mentioned in other post the PCM may see a coolant issue, trips SES
and if the CES Check Engine Soon light does not come on, then I assume the PCM has not triggered any DTCs

 

[Mick Howes]

Thanks for all the info teamzr1, when I take the car in to the garage will give this to them too, when they carry out diagnostics check.