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Discussion Starter · #1 · (Edited)
Now, just after leaving work i got the P1620 & P1343.


P1620 Map Cooling control circuit signal high

P1343 ....


OMG! i replaced thermostat 04-16-2011.. :banghead:


seriously? my thermostat... this ridiculous...

Order the OEM :http://www.pelicanparts.com/bmw/catalog/shopcart/BE46/POR_BE46_WATpmp_pg3.htm#item17

My Thermostat DIY i did :http://forum.e46fanatics.com/showthread.php? t=837476&highlight=:hmm:

NOTE: I bought the wahler OEM SUPPLY : Failed in 1 year.

Pelican parts would sell me 116$ genuine thermostat , send it too me... Then refund me 64$ from failed thermostat.


Should i just assume i have failed thermostat?> go ahead and replace it with genuine brand...and not OEM WAHLER or apparently ill have to send them back my thermostat every YEAR. ?

Use Diagnostic on Board. Press 19 then go 7 to check Coolant temp?
 

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If your thermostat fails you WILL know! Thermostat has a spring in it and is designed to fail in a stuck open position, therefore your car will never reach operating temp. Is this the case????

In some cases the thermo can fail in a stuck closed position in which case your car will always overheat. Is this the case???

The P1343 is a misfire, you need better diagnostic tools, whatever you're using now is a cheap china tool that gives generic codes. You need to find out which cylinder is misfiring, then find out is its one of your spark lugs thats bad (sometimes if your engine burns oil, the oil contaminates will get on the plug and ruin it) or if its a coil.

Either way, if your car is warming up fine to the operation temp then your thermo is working absolutely fine
 

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Discussion Starter · #4 · (Edited)
If your thermostat fails you WILL know! Thermostat has a spring in it and is designed to fail in a stuck open position, therefore your car will never reach operating temp. Is this the case????

In some cases the thermo can fail in a stuck closed position in which case your car will always overheat. Is this the case???

The P1343 is a misfire, you need better diagnostic tools, whatever you're using now is a cheap china tool that gives generic codes. You need to find out which cylinder is misfiring, then find out is its one of your spark lugs thats bad (sometimes if your engine burns oil, the oil contaminates will get on the plug and ruin it) or if its a coil.

Either way, if your car is warming up fine to the operation temp then your thermo is working absolutely fine
Yea.. you absolutely right about the failing OPEN or CLOSED.

stuck Open- Temp gauge wont warm up all the way to the middle.

Stuck Closed: Over heat.

I will test it tomorrow morning on my way to work. (Temp gauge should get to operating temperature after 15 minutes drive) if not... its failed thermostat....


NOTE: i have not touched my thermostat sensor or area sense i put the new one in.
 

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Give it a good 20 min, I dont know whats the weather like where you live.

Maybe take the plug off the sensor and see if its plugged with dirt or anything then put it back
 

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Discussion Starter · #7 · (Edited)
Give it a good 20 min, I dont know whats the weather like where you live.

Maybe take the plug off the sensor and see if its plugged with dirt or anything then put it back
weather here 73 *F

I will try to UNPLUG and clean sensor.

Looking out for the CLOSED & OPEN symptoms :(

I know it's normal for PLUGS to fail.

but is it normal also for oil to get on it?

P1343 on my search results came up on BAD SPARK PLUGS < plead guilty lol
 

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Use advanced search for both your codes.

1620 seems to point to therm.

Only other hope for you is that you haven't opened up your cooling system to check on the level in a long while and that you're low on coolant and/or you have, because you're lowish, gotten an air bubble that passed by the temp sensor and triggered this code.

Do you have a CEL and that's what caused you to stop and read codes?

You sure that when you're on the highway, the temp gauge isn't moving a little to the left? Have you done cluster test to monitor coolant temps?

Therms fail...even new(ish) ones. If you read the threads with 1620, you'll see instances of this.

If you don't have a CEL, still check your coolant level...and just read a lot of threads on both your codes. I'm sure some simple diagnostics will be suggested. Cleaning contacts, checking wires is always a good idea...though your signal is high...I'm not sure what that exactly means, but it sounds like it thinks it ought to stay open more often than it thinks it should or something. That's a random guess for your random problem.

If so...maybe it is just low coolant or coolant in really bad shape...because when you did the therm, you only replaced what you lost and didn't otherwise change out the coolant entirely...which should be done every 3-4 years...technically.

Back to you...GL!
 

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Suggest you read the link in my signature below for the Hidden OBC menu, look up 7.0 Engine Coolant and read directly on the dashboard.

This should give you some insight as to what is going on.

These motors run pretty warm, you need to check the overall swing of the temps when driving and you can get a good idea about what my be going on.

BTW, most German stats last between 1-3 maybe 4 years before problems show up.
 

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Discussion Starter · #10 · (Edited)
Ah guys... my car is getting me crazy nuts... almost to the point to trade in for something else ... WHY!!! :tsk:

How do i get P1620-P1343 ... Then 70 miles later on cold start... Bow! CEL GONE! :eek:

Temp gauge warms up to the middle like is suppose too! ... So how the heck im getting P1620 and temp gauge works perfectly? :hmm:

Then on warm up "No codes"... right when temp gauge leaving BLUE COLOR i get 6^ codes! -_-' :banghead: :censor:

p1349
p1343
p0300
p1620
2 other pending!

I have no clue what to do! .... Just go ahead and TAKE IT TO THE STEALERSHIP ? :banghead::banghead::banghead::banghead:

what is ENGINE COOLANT Temperature SWITCH?
 

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Discussion Starter · #13 ·
There is an engine block temp sensor...I'll look for it on mine and then you can find it on yours through realoem.com

I also think the engine gets signals on temp from air intake temp sensor, outside air temp, coolant temp sensor too...search "Shanneba" for temp sensors. If anyone wrote about it here, it's him!

BRB

So, first thing, if it was me, I'd check connections and wires, especially if you'd been around either place doing any work.

#13--temp sensor water/oil


#3--another temp sensor water/oil

'

Found out the answer, So we do really have 2 more sensors for temp.

Meaning, my thermostat works perfectly on GAUGE.

I will replace this TWO COOLANT TEMP SENSOR. how difficult should it be?
 

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'

Found out the answer, So we do really have 2 more sensors for temp.

Meaning, my thermostat works perfectly on GAUGE.

I will replace this TWO COOLANT TEMP SENSOR. how difficult should it be?
The number 13 water/oil temp sensor in the top diagram is for OIL temperature only.

It is the same part number as the number 3 temp sensor in the block in the lower diagram, used for coolant temp only.

There is also a coolant temp sensor in the lower radiator hose, it is used for coolant temp info to control the electric fan, has nothing to do with the gauge.
 

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Discussion Starter · #15 ·
The number 13 water/oil temp sensor in the top diagram is for OIL temperature only.

It is the same part number as the number 3 temp sensor in the block in the lower diagram, used for coolant temp only.

There is also a coolant temp sensor in the lower radiator hose, it is used for coolant temp info to control the electric fan, has nothing to do with the gauge.
Okay shanneba, so its worth less to replace #13 on the diagram ,

But how about the #3 as you say> "It is the same part number as the number 3 temp sensor in the block in the lower diagram, used for coolant temp only.

What really throwing me off from replacing my thermostat is due to working properly. Even when erasing Check engine light and unplugging the sensor it comes back.
 

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If the ECU does not get a signal because you unplugged the sensor, it should throw a code because it can't get a valid signal/input.

http://wds.spaghetticoder.org/en/zinfo/HEL0498FB1214_M0TMO.htm
Coolant-temperature sensor

The coolant-temperature sensor is screwed into the cylinder head and registers the temperature of the coolant by means of its variable resistor (NTC= negative temperature coefficient).
Among other things, the coolant temperature serves as a measured variable for the following functions:
Start volume calculation
Injection volume calculation
Nominal idle speed
In the event of the coolant-temperature sensor failing, a fault code is entered in the DME control unit and a substitute value is calculated from the value of the intake air temperature sensor with the aid of a temperature model.


That should be a different code from your P1620 code. Probably a P0117 or P0118 code for the coolant temp sensor.

What happens if you plug in the coolant temp sensor and the thermostat, drive normally (no heavy foot on the throttle and no rpms above 3000)?
I suspect you would not set a code as your operating coolant temperature seems close to normal.
You thermostat may have an internal wiring fault.

The connector to the thermostat should normally not have voltage applied until the ECU senses a higher load or rpm> ~3000 and the ECU applies 12 volts to the thermostat to force the thermostat open farther to cool the engine. That is how the MAP controlled thermostat operates. If there is an issue with the thermostat internal wiring the ECU may be sensing the "high" current and setting the code.
The P1620 code shows as "MAP cooling thermostat control circuit high" that would be when applying the voltage. If you drive a couple times without heavy throttle or higher rpms the MAP cantrol would not be used, that could cause the check engine light to turn off since the ECU would see two drive cycles without detecting the MAP thermostat control error.

BMW MAP thermostat info:
http://wds.spaghetticoder.org/en/zinfo/HEL0498FB1214_M0KFK.htm
 

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Discussion Starter · #17 · (Edited)
If the ECU does not get a signal because you unplugged the sensor, it should throw a code because it can't get a valid signal/input.

http://wds.spaghetticoder.org/en/zinfo/HEL0498FB1214_M0TMO.htm
Coolant-temperature sensor

The coolant-temperature sensor is screwed into the cylinder head and registers the temperature of the coolant by means of its variable resistor (NTC= negative temperature coefficient).
Among other things, the coolant temperature serves as a measured variable for the following functions:
Start volume calculation
Injection volume calculation
Nominal idle speed
In the event of the coolant-temperature sensor failing, a fault code is entered in the DME control unit and a substitute value is calculated from the value of the intake air temperature sensor with the aid of a temperature model.


That should be a different code from your P1620 code. Probably a P0117 or P0118 code for the coolant temp sensor.

What happens if you plug in the coolant temp sensor and the thermostat, drive normally (no heavy foot on the throttle and no rpms above 3000)?
I suspect you would not set a code as your operating coolant temperature seems close to normal.
You thermostat may have an internal wiring fault.

The connector to the thermostat should normally not have voltage applied until the ECU senses a higher load or rpm> ~3000 and the ECU applies 12 volts to the thermostat to force the thermostat open farther to cool the engine. That is how the MAP controlled thermostat operates. If there is an issue with the thermostat internal wiring the ECU may be sensing the "high" current and setting the code.
The P1620 code shows as "MAP cooling thermostat control circuit high" that would be when applying the voltage. If you drive a couple times without heavy throttle or higher rpms the MAP cantrol would not be used, that could cause the check engine light to turn off since the ECU would see two drive cycles without detecting the MAP thermostat control error.

BMW MAP thermostat info:
http://wds.spaghetticoder.org/en/zinfo/HEL0498FB1214_M0KFK.htm
Oh dam! As to my understanding you telling me not to change those sensor I mention but to "use my warranty and get the new thermostat because what failed was THE THERMOSTAT even if the gauge is reading perfectly operating temperature 95 and the CODE problem is faster 3000RPM.

so its more like something electronic went bad and not the whole thermostat unit?
 

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Oh dam! As to my understanding you telling me not to change those sensor I mention but to "use my warranty and get the new thermostat because what failed was THE THERMOSTAT even if the gauge is reading perfectly operating temperature 95 and the CODE problem is faster 3000RPM.

so its more like something electronic went bad and not the whole thermostat unit?
Yes, your coolant temp sensor seems to be working correctly. No code for it. The temp is close to the "normal" range according to the OBD menu.

It is the internal heating mechanism of the thermostat that has a problem (or your wiring/connection to thermostat from the ECU)

Your thermostat will continue to function as a normal (non mapped) thermostat, if you run your car hard it will not be able to lower the coolant temp as it normally would if the MAP control part worked, eventually the ECU will richen the air/fuel mixture and retard the ignition timing to keep the engine cooler, that will affect your performance. Also if your coolant temp gets to 113 C the ECU will not be able to force the thermostat open further to cool the engine, at that point you will see your gauge climb above the mid point toward overheating.


If you saw a P0128 code, "Coolant thermostat (coolant temp below threshold)" or P0125 "insufficient coolant temp for closed loop operation" it would mean your thermostat is stuck open and the engine isn't getting warm enough.

BMW Codes reference - find your ECU/Engine and production date in the left hand frame for your ECU specific codes:

http://www.motodok.com/Documentation/Files/BMW/bmw-pcodes.pdf
 

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Reviving this ahead.
Gus, did you ever resolve this?
I have a 1620 code showing, but car seems to warm up OK and not overheat.
For what it's worth, I just had a blown head gasket, meant to replace the thermostat, but apparently didn't order it for my mechanic, so he reused the old one.
I am also getting a 0056 O2 sensor code. I'm wondering if that could be related to the 1620, since they both have something to do with the ECU input. I'm guessing not, but...
 
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