co pot. buy new, used or repair

Started by C0UP3, November 01, 2014, 10:16:07 PM

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C0UP3

I think my co pot is shagged. It's makes no difference to afrs (aem gauge) whether it's unplugged or not and turning it does nothing. I am struggling to even get a resistance across pins 1 and 3.

Only UK place I can find new ones is OCD @ 135quid.
Is it worth risking a 2nd hand unit or is it possible to repair it?

Alexiskayak_7

Its not a risk buying second hand one. You can test it before buying one.

G40supercharged

It should be possible to repair it. If I remember correctly, my previous G40 had the white side cover missing off the CO pot. All that is inside is a 2 pin air temperature sensor and a multi turn trim potentiometer. It's likely that the trim pot variable bit has broken as they are quite fragile. It should be possible to get a new trim pot for a quid or so (RS or Maplin may do them) and solder it in. You will need to measure the trim pot value with a multimeter set on resistance; it will have 3 pins. 2 of them will show a fixed resistance. Disconnect from ECU before measuring.

Jezza-7

Dub_diaster has 2 good working ones.

Or give me a pm for price and i can post it on behalf of him.

C0UP3

Trouble with measuring resistance is it doesn't work so I get no connection I will take it apart. Hopefully and most likely it will have codes on it which will match and I can get a cheap new thermister and new potentiometer from maplins

G40supercharged

Quote from: C0UP3 on November 03, 2014, 04:22:46 PM
Trouble with measuring resistance is it doesn't work so I get no connection I will take it apart. Hopefully and most likely it will have codes on it which will match and I can get a cheap new thermister and new potentiometer from maplins

The pot inside the sensor has 3 pins. Two of them connect to each end of the resistance and the third is the moving part that sets the variable resistance. The third bit will be the broken part. If you open it up you can measure the two pins at each end to get the overall resistance value. But as you say, the value is probably written on it (at a guess it will be 1K). I doubt that the temperature sensor bit is broken; I would leave that in place. If you don't get an exact matching one to replace it, it will give the ECU the wrong value. Alternative botches are to wire in a pot outside of the sensor itself, or put in a fixed resistor (500R seems a popular setting). I'm guessing your one is currently open circuit as far as the ECU is concerned.