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AndyC_67

E46 330ci 2004- Thermostat Error Code

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Hi I have a E46 330Ci 2004 (~150000 miles) It has been throwing an error code 123 "MAP Cooling Thermostat" see attached screen shot.

I have had this for a long time. Each time I clear it - it comes straight back. One thing to note is that the car runs as sweet as anything. Starts first time, idles smoothly. I get good mileage for the car (~33mpg on long runs, nearer to 28 around town). In a nutshell you would not know anything was wrong.

I'm tempted to say "if it aint broke don't fix it" as the car runs so well. However, I wouldn't mind fixing it. Anyone have any views? Also where can I find it on the engine?

*Note the second error shown has been resolved!*

Thanks all!

Error Code (Medium).jpg

Edited by AndyC_67

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It's a code for the electrical heater in the thermostat. This heater is controlled by the ECU and makes the 'stat open more and cool the engine further when you drive at full throttle on a hot engine, and this helps to keep the ignition timing advanced for optimum power and efficiency when driving hard.

It's not going to cause any harm in the short term (or even long term perhaps).

To cure the code you need a new 'stat, I bought a Wahler 'stat for mine from Carparts4less for about £50. This is the OEM brand so should hopefully last another 10 years or so.

Edited by Tim-Ci

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Perfect! Thank you very much for that. I have not done one of these before on a BMW. I take it there is only one thermostat or is this a special one? I'm used to thermostats being in the coolant line.....is it the same one? Sorry....I guess I could look it up......

Thanks again!

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No problem Andy.

Yes there's just one 'stat on the 330is. It sits on the front of the engine, has two coolant pipes connected to it and an electrical plug (for the heater part that's gone wrong on yours). I hear some of the 'stat's can have issues with leaks over time through the electrical connector and into the wiring, which can affect the wiring and the engine ECU, so I would reccommend getting a decent make such as the OEM Wahler type.

If you're going to need new antifreeze the Comma G48 is the right spec., and might be a bit easier to find than the BMW coolant. If you use the concentrate and not the ready mixed stuff I would recommend mixing it with the distilled water available in car shops. I think the capacity is about 8.5 litres.

This guide shows basically how to do it: http://forum.e46fanatics.com/showthread.php?t=665860 To give a bit more detail about removing the fan, I think there's a torx bit or two at the top, a plastic pin/plug thing holding it too, then disconnect the wiring and lift the fan out. I didn't see the need to use sealant unlike that guy, the 'stat has a seal built in to it.

I drained my coolant from the drain plugs at the bottom of the radiator/tank unlike the guy who wrote the guide above, this guide shows how to do it (and bleed the system properly afterwards): http://www.bmw330ci.net/maintenance/coolant.php

Edited by Tim-Ci

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