Mightyleader
Member
Hey all,
I’m new to this so I’m posting to get some idea that my troubleshooting is on the right track.
Here’s the symptoms:
We’d driven on the motorway for about 90 minutes, pretty constant speed around 65-70mph. Traffic was moving so there were no periods stopped or doing little movements in 1st or 2nd gear.
The temperature gauge has, since I got the car, been temperamental, sometimes it will sit straight up at 90, intermittently it will just be bang over at the left, as if it were not reading at all. Same on this journey, it was intermittent.
Approaching the junction to join the M3 southbound on the M25, the traffic was queuing badly and we spent sometime sitting edging forwards.
At this point the temp gauge was again not giving a reading and the Engine Warning Light and EPC light came on.
There was no loss of power, no limp mode engaged.
My partner did a bit of googling and reading on here and all signs pointed to the coolant temp sensor on the engine.
I didn’t really want to stop in the junction, plus the M3 is a ‘smart’ motorway with no hard shoulder, and given the car seemed to be running fine and the fan was working, we elected to take it easy and keep going till we got to Fleet Services.
As a precaution I got the AA out, and while waiting thought through the issue. Here’s my assessment, which the AA guy later agreed with, but your collective wisdom might know better...
The coolant temp sensor connects to 2 circuits (hence having 4 wires) the first is to feed data to the Temp Gauge in the dash. The second is to provide data to the engine management unit (we call that a CCCU is that right?).
So a faulty connection somewhere between sensor and gauge might cause the loss of reading.
Equally a faulty connection could trigger the car brain to show a warning light if it couldn’t read from the sensor.
The first of these happens regularly, the second only this once so far.
Having had a look at the sensor, the cable looked a bit kinked as it connects to the sensor and the wires were visible for about 10mm where the insulation had pulled back.
Wiggling it, carefully, with a rod, caused the temp gauge to alternate between working and not. The warning lights for engine and EPC did not make a reappearance.
The AA mans VCSD box didn’t pick up an error and was getting good readings from the sensor, presumably via the EPC.
We loosened the cable to give it a little slack and I rolled the dice and drove home.
Only once did the temp gauge stop then recover itself. The lights did not make another appearance.
So my thought is to replace the sensor (part ordered) and have a look at the condition of the cables, pins and connector. Add better insulation and seat it with more slack.
Comments?
I’m new to this so I’m posting to get some idea that my troubleshooting is on the right track.
Here’s the symptoms:
We’d driven on the motorway for about 90 minutes, pretty constant speed around 65-70mph. Traffic was moving so there were no periods stopped or doing little movements in 1st or 2nd gear.
The temperature gauge has, since I got the car, been temperamental, sometimes it will sit straight up at 90, intermittently it will just be bang over at the left, as if it were not reading at all. Same on this journey, it was intermittent.
Approaching the junction to join the M3 southbound on the M25, the traffic was queuing badly and we spent sometime sitting edging forwards.
At this point the temp gauge was again not giving a reading and the Engine Warning Light and EPC light came on.
There was no loss of power, no limp mode engaged.
My partner did a bit of googling and reading on here and all signs pointed to the coolant temp sensor on the engine.
I didn’t really want to stop in the junction, plus the M3 is a ‘smart’ motorway with no hard shoulder, and given the car seemed to be running fine and the fan was working, we elected to take it easy and keep going till we got to Fleet Services.
As a precaution I got the AA out, and while waiting thought through the issue. Here’s my assessment, which the AA guy later agreed with, but your collective wisdom might know better...
The coolant temp sensor connects to 2 circuits (hence having 4 wires) the first is to feed data to the Temp Gauge in the dash. The second is to provide data to the engine management unit (we call that a CCCU is that right?).
So a faulty connection somewhere between sensor and gauge might cause the loss of reading.
Equally a faulty connection could trigger the car brain to show a warning light if it couldn’t read from the sensor.
The first of these happens regularly, the second only this once so far.
Having had a look at the sensor, the cable looked a bit kinked as it connects to the sensor and the wires were visible for about 10mm where the insulation had pulled back.
Wiggling it, carefully, with a rod, caused the temp gauge to alternate between working and not. The warning lights for engine and EPC did not make a reappearance.
The AA mans VCSD box didn’t pick up an error and was getting good readings from the sensor, presumably via the EPC.
We loosened the cable to give it a little slack and I rolled the dice and drove home.
Only once did the temp gauge stop then recover itself. The lights did not make another appearance.
So my thought is to replace the sensor (part ordered) and have a look at the condition of the cables, pins and connector. Add better insulation and seat it with more slack.
Comments?