1990 740 GL with a B230 engine

I just replaced the head gasket,thermostat, belts hoses, oil, cleaned flame trap and its running good.

But check engine light comes on and I ran the codes....

i got

223 - Idle valve signal
321 - cold start signal missing
224 - coolant sensor
143 - knock sensor missing

So im thinking is there a wire harness for sensors under the intake which I could have pulled loose doing all this work....if so where its it?

Its running great better then ever as long as I keep idle up to 900-1000 rpm

 

the coolant sensor is under the intake mani, in the cylinder head, under runner number 3. check the connects on all those sensors.... Did you have a Check engine light before the gasket job?
how many miles does it have? We did a vavle adjustment not to long ago, and that did wonders!

Wait for the experts to get on

 

213,00 miles


Check engine light was on since it overheated and blew head gasket...
Actually warped head had it machined ect ...

Maybe the heat messed up the sensors on intake....


Check engine light was not on before the gasket blew..

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Update:
I reset the computer afer checking wires on coolant sensor..(They are Ok)
Maybe coolant sensor is shot....

I noticed the sensor attached to the intake has a broken wire which seems to have been re routed (by a mechanic previously) Its been run from the sensor to the starter....which is strange....

codes
321 - Cold start valve - Is this the sensor on the intake with the re routed wire...

224 - Coolant sensor

143- Knock sensor (anyone know where it is ; Im unsure)

 

Was loose wires on Harness by the firewall (passenger side)...

Check engine light off......


That harness connects the ECU to the sensors under the manifold....

 

Glad it is solved....Congrates! I believe those wires by the passenger firewall lead to the ecu...

FYI....the knock sensor is in the block:
the arrow pointing to it.

 

That 230 is squeaky clean.......

Only my cylinder head looks like that as it was acid washed at the machine shop..

I glad it isnt the ECT as It would be my 3rd time taking off the intake this week..lol

 

I'd eat scrambled eggs off that motor.