2000 502 mag mpi engine code 14
 

anyone have any ideas on what else could be throwing a code 14 error i changed the sensor checked for voltage and checked grounds also swaped computers any help would be great thanks

Just getting back into I/O after 20yrs outboards but I found this which may help. Did U check ohms for each wire from ECM to sensor(pin to pin)

14 MAP sensor

Message your email and can send the PDF doc. Not sure if it's 100% accurate

Is this a OEM stock app ? It should be MEFI 3 --- Fault code 14 is engine coolant temp sensor circuit open / low temp

Engine coolant temp = faulty sensor and or open circuit. also ECT high = meaning sensor output high and that = cold and or low temp

With that said if all is good and engine coolant temp sensor is a known good sensor - would have to ask what gasket was installed for the T stat housing and did you gasket sealant -- if so that is a totally wrong install. Proper rivet button gasket needs to be installed and NO GASKET SEALANT period on anything.. All needs to be clean and as rust free as possible. Also change your T stat and use the proper cork gasket for the T stat internally in the housing.

Make sure all connections and grounds even at the ECM for the ECT sensor circuit is all good, clean and tight. No corrosion period in all areas, no splices or broken wires or connections. . .

look at Merc Manual 23 pg 5F-22

As BUP said engine coolant temp sensor faulty, or T stat housing isn't grounded properly . (besides a wiring issue witch were hopping it isn't)

The Engine Coolant Temperature (ECT) Sensor uses a thermistor to control the signal voltage
to the ECM. The ECM applies a voltage on CKT 410 to the sensor. When the engine
coolant is cold, the sensor (thermistor) resistance is high, therefore, the ECM will see high
signal voltage. As the engine coolant warms, the sensor resistance becomes less, and the
voltage drops. At normal engine operating temperature, 160-180°F (71-82°C), the voltage
will measure about 1.5 to 2.0 volts.

It is a mefi 3 the computer has been re programed but i did swap with the other motor and it did not make a difference i just put a new thermostat with the correct gasket the only other thing i did was change the connector that plugs int the ect sensor but i soldered the wires and the code was there before i did that i will look into the voltage i also swaped sensors with the other motor to see if the new one was bad thanks for evryones input i hope it helps