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[MotormanV6]

The MV6 (1999 - Mini Facelift) has just passed it's MOT with flying colours, after installing some nice new Kilen Springs to replace the broken one (thanks for the help and advice on that job). Now the bad news....its suddenly struggles to start, e.g. 4/5 attempts, but once running and warmed up its absolutely tickety boo. Did paperclip test - code 15. Before I start stripping it all down to replace the ECU Temp Sensor, does this sound like the correct diagnosis?  Thanks

[Nick W]

Live data from the temp sensor before you replace it unnecessarily. It's a cheap part, but a fair amount of work and probably isn't the fault.


Check the crank sensor and MAF readings while the scan tool is connected.


I'd be thinking failing fuel pump, and would be checking the pressure and fuel flow while cranking.

[MotormanV6]

Unfortunately I don't have a scan tool (my X30XE isn't ODB-II compliant) and I can't afford an Opel Scan device. So I'll check the fuel supply pressure on cranking as a starting point.

[Doctor Gollum]

Have you recently had the Ecu temp sensor unplugged?

If yes, the chances are the plug has been swapped with the purge valve... The sensor is 5V, the valve 12V so you can imagine the effect on the sensor.

If no, then you need to replace the ecu temp sensor

[Doctor Gollum]

I should add, the fact that it eventually starts whilst hot suggests a faulty sensor.

Swapping the plugs over basically causes it to overfuel as it assumes that it's - 40. Once warmed up it will only fire with the fuel pump fuse pulled.

[MotormanV6]

Thanks for that Dr.G. No, I haven't swapped the plugs over (not been tinkering in that area...yet!). It starts immediately when hot, its just it really struggles when cold, to the extent of sometimes eventually almost flattening the battery. The temperature gauge on the instrument panel has never worked properly so I think I'l replace both sensors whilst I've got the intake bridge off and working in that area.

[Doctor Gollum]

Makes sense

£10 or so and a couple of knuckles we'll spent.

When you do it, simply remove the inlet elbows, undo the four bolts on the plenum and lift it forward a couple of inches. No point disturbing a whole load of gubbins unnecessarily 

[MotormanV6]

Oh, ok, I'l try that when the bits arrive. I've just ordered them....90541520 for the ECU one and 90510850 for the gauge one. Hope that's the correct numbers. I'm guessing its probably a bit easier with the scuttle thing removed?

[Doctor Gollum]

Oh, ok, I'l try that when the bits arrive. I've just ordered them....90541520 for the ECU one and 90510850 for the gauge one. Hope that's the correct numbers. I'm guessing its probably a bit easier with the scuttle thing removed?

Read the instructions

Only need to move the plenum.

You'll note that I said move and not remove

Pulling the scuttle will cause more issues than it solves.

[MotormanV6]

Right....Remove the two elbows, four bolts on the plenum, lift forward. I'll go and do it now. I'll keep you posted. Thanks.

[MotormanV6]

Job done, all back together....Primed fuel line and pressed the starter....started immediately. Going a lot better than before. I got Bosch Part No: 0280 130 093, apparently they're two different ones: Blue - before engine no 08135541 & Black after. Anyway my engine was in the after category so got the black one.

No luck with the temp gauge, changed the sensor but no difference, can't spend any more time on this one, so I'll leave it.

Thanks for all the help and assistance. 

[Doctor Gollum]

Temp gauge is a single wire... Spade terminal to the sensor, (ground to test gauge with the ignition on), this is a 15cm wire that plugs into another plug* which then runs directly to the gauge

*in the loom near the large injector plug iirc

[MotormanV6]

OK, I'll might give it a go later this week. What should happen when I ground the connector with the ignition on?

[LC0112G]

OK, I'll might give it a go later this week. What should happen when I ground the connector with the ignition on?

Grounding and ungrounding the terminal should cause the dash temperature gauge to go from fully cold to fully hot in a few seconds.

[MotormanV6]

Great, thanks for the info.

[BazaJT]

Can anyone confirm that engines after 08135541 should have a black CTS? My engine is 08461362 and has a blue CTS so maybe the wrong one has been fitted in the past[my car is a F/L 3.0]

[Doctor Gollum]

Can anyone confirm that engines after 08135541 should have a black CTS? My engine is 08461362 and has a blue CTS so maybe the wrong one has been fitted in the past[my car is a F/L 3.0]

Does it work?

[dave the builder]

You can't just say it needs a blue one or a black one , there are so many aftermarket manufacturers that use different colours for the same part .
I've seen blue, grey, natural and black

[BazaJT]

Well DG the engine starts and runs the fans kick in[all three at the same time]and then don't stop until after the engine has been turned off.Air con doesn't work[never has since I've owned it]but the fans did used to behave as they should,so something isn't right.

[Doctor Gollum]

The fans are almost completely independent of the ecu. There's two thermoswitches on the radiator. These are the primary fan controls.

The only time the ecu would request the fans is if the aircon is switched on, no aircon means that the fans are self regulating

I forget which thermoswitch controls which fans, but it stands to reason that if one is failing, tother won't be far behind, so would swap both and report back

The aircon not working may also be related, depending on the cause, and not having it working makes diagnosis of the fans a bit harder as the aircon wiring is directly connected to the fans... that's to say the aircon not working could be electrical rather than just low refrigerant

[Eyal2002]

The thermoswitch activates the fans that are on the radiator towards the engine. When looking at the radiator from the engine side the thermoswitch plug is visible. If disconnected, the plug (2 or 3 contacts) can be safely shortened with a paperclip or wire (one is ground, other wires receive that ground for half/full fan speed). If all is healthy (fuses etc) then the two said fans should kick in regardless of key/ignition position.

[BazaJT]

Don't know original reason for air con not working but the bearing for the pulley on the compressor is now shot so I've fitted a shorter non-aircon auxilliary belt to by pass the compressor.From what I can see the lower thermoswitch would need the radiator to come out to get the clearance for a spanner? I know the top switch is a three pin on mine.

[Eyal2002]

I don't know about lower thermoswitch, I don't have it (2.6L), or if it is indeed one (maybe temp sensor?).
Anyway the 3-pin one is controlling the fans. Again, make a temporary U-shape from a metal clip, unplug it and short the ground to any of the others. You can send a temporary wire from the battery negative terminal to each one of the three, two of the wires should respond by turning the fans on, and if so then the one not responding is the plug's ground.
Note that as this is always a live plug, if you short it with a paperclip and fans are on then it can deplete your battery after a good few minutes. And of course always EXPECT the fans to kick in, so before troubleshooting clear them from wires, tools, fingers etc.

[Doctor Gollum]

The lower one may be region dependent...

UK cars have 2