Cummins ISL 400 HP code 151 clears then comes right back on with cold engine .

[jegall]

My scangauge D and dash gauge both read normal temperature but keep getting code 151 thats high coolant temperature . Anyone know if more then one sensor.

 

[Robert U]

There is two sensors. One for the ECM and one for the temp gauge.

 

BobU

[jegall]

Any idea location ?

[jacwjames]

I downloaded a document from Cummins Quickserve that lists all the sensors they install, it kind of shows locaiton but a little vague but Cummins uses sensors that have a wiring connector plug end.  On my ISC engine is show these two for engine, one is oil temp and one is coolant.

https://shop.cummins.com/SC/product/cummins-temperature-sensor-3408345/01t4N0000048cJpQAI

 https://www.diamonddiesel.com/oil-coolant-fuel-temperature-sensor-for-dodge-cummins-engines-alliant-power-ap63605-oem-part-s-4954905-3865346-3096153-4088750-4088751-ap63605

Monaco usually installed sensor with a wire connector, attached is a parts listing for the coolant temp on my coach, in my case it is located on top of engine on the pulley end near the alternator.  This is the picture

You can create an account on Quickserve, once you have an account register your engine using the SN.  It is a great resource. 

There is also a Fault Code lookup, it will provide an overview explanation but then within the document there will be detailed troubleshooting guide. 

Since you are actually getting a code it is the Cummins sensor that is sensing the high temp, it sends signal to ECM.  Monaco sensors report to the gauges.

Control Module sensors 3408429 oil pressure sensor.pdf 1 Water Temp Sending Unit.pdf

Edited May 7 by jacwjames

[Robert U]

On my ISC the ecm temperature sensor is located just below the thermostat which is located below water pump. 
 

Bob U