Question about 1999 Ford F150 Regular Cab

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U1073 scp code

My engine over heated last week and I had the temp unit replaced. Now my temp gage goes to normal then up to max heat and after I put on the heater the temp goes back to normal. I am getting an error coade of U1073 SCP and need to know how to fix it.

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Hi MaddMD!

This is partly an answer to part of your question, and part clarification request

According to: the U1073 SCP is defined as:
"U1073 SCP (J1850) Invalid or Missing Data for Engine Coolant PCM REFER to Powertrain Control/Emissions Diagnosis (PC/ED) manual"

Okay.... I need to research what exactly the above means, but I also need a little more information from you.

  • What engine do you have?
  • Were there any malfunction indicator lights (MILs)?
  • How did the overheating occur (stopped at idle, going down the road, A/C on or off?), and how drastic was it? (i.e.: Was there loss of engine oil, any significant smoking or steam out of the engine bay, significant loss of power?)
  • Do you know what caused it to overheat? (Low coolant, fan failure, broken belt, water pump problem, stuck thermostat)
  • What prompted you to change the temp sensor?
  • Is it an electric or engine driven radiator fan?
The way you describe the situation now, without considering the code, it sounds like the radiator fan is not moving enough air across the radiator to remove heat from the coolant. Turning the heater on causes the heater core to act as a kind of substirute radiator and thus lowering the engine temp. This can be verified, if the truck is driveable, by going down some open road with the heater on to cool the engine, switching off the heater and then see if the temp comes back up while moving at least 30 mph or if it stays down. If it stays down while moving, try stopping and idling for a couple of minutes and see if the temp then goes hot... If so, the fan is not working as it should and should be looked at. Don't let it get too hot, and see if you can get it to an AutoZone to have them perform a free diagnostic scan and see what OBD-II trouble codes are set.

Get back to me by posting a comment to your problem with whatever further information you can gather and also by sending me an e-mail at so that I'll know to check that information, and in the meantime I'll check with some of my Ford tech friends as to the signicance of the U1073 SCP code.


Posted on Jun 19, 2008


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Does the 98 Ford F-150 5.4 triton have two coolant sending units? I found the one on the intake and replaced it and still no gauge.

Has CHT - cylinder head temp. sensor . This sensor is a input to the PCM - engine computer . The PCM sends engine temp info on serial data network to the instrument cluster . I/C has a microprocessor inside . Have it check for DTC'S - diagnostic trouble codes . Not OBD2 codes , B - body codes . The gauge could be the problem , which means replacing the instrument cluster .
Engine coolant temperature information is received by the instrument cluster from the PCM over the SCP network. Temperatures over 121°C (275°F) will display hot (H). If the engine coolant temperature data is missing or invalid for five seconds, the instrument cluster will move the engine coolant temperature gauge below the cold (C) position.
The best way to diagnose this is with a scan tool , factory or a professional type . Know how the system works and not replacing parts is the proper way to diagnose .
U1073 D073 SCP (J1850) Invalid or Missing Data for Engine Coolant PCM CARRY OUT the PCM self-test.
  • A single gauge does not return to zero with the ignition switch off
  • Instrument cluster.
  • INSTALL a new instrument cluster; REFER to Instrument Cluster . TEST the system for normal operation.

  • Incorrect temperature gauge indication
  • Circuitry.
  • Instrument cluster.
  • PCM.
  • Engine coolant temperature sensor.
  • GO to Pinpoint Test F .

I should also point out that if the temp sensor were bad the vehicle may not run right .
Using the factory scan tool
Trigger instrument cluster active command ENGCOOLNT. Monitor the engine coolant temperature gauge while adjusting the ENGCOOLNT active command to read 50% and 100%.
  • Does the temperature gauge start at cold, move to half at 50%, and full hot at 100%?
Yes REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.

No INSTALL a new instrument cluster; REFER to Instrument Cluster . REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
Your best bet , take it to a qualified repair shop !

May 29, 2017 | Ford Cars & Trucks

1 Answer


first thing to do is open the radiator cap (when cold) if you have one, other wise look in the recovery bottle and make sure that it is half full of coolant. if full, start the engine and let the engine warm up to normal temp the heater on and on max temp and max fan control. watch the temp gauge and make sure the temp goes to the normal operating area and does not overheat the engine. if temp is ok and you have heat that is hot as normal then everything is ok.if no heat and temp is to high then thermostat maybe bad? if engine temp is ok and no heat then you may have blockage in the heater core and or hoses

Jun 11, 2014 | 2004 GMC Canyon

1 Answer

Temp gage on dash stays at low and i have no heat coming out from any vent just air,

If you have checked the radiator coolant level and it is correct, I would think that maybe your thermostat is stuck in the open position which will not allow your engine to come to the proper operating temperature.

Dec 29, 2012 | 2002 Chevrolet Cavalier

1 Answer

The high temp gauge will max out and then back to normal. Also the heat will not work then kick in all of a sudden.

Let me guess...When the temp gauge goes hot, the heater goes cold, and vice versa? Check your coolant level first in the radiator (when the engine is COLD) and also in the overflow reservoir. ONLY use a 50/50 mix of coolant and water, using the same COLOR coolant that is already in the radiator (if it's green, buy green, if it's orange/red, buy orange/red). Next thing to have checked/replaced is the thermostat which is inside the cooling system of the engine. Finally, and the most expensive, have the water pump checked/replaced.

I would put my money on low coolant level in the radiator. As the engine heats up, the coolant will "surge" through the system as the water pump tries to **** air through the system due to low coolant level. If the coolant isn't flowing, the heat can't escape the engine block and it starts to overheat.

Dec 19, 2010 | Chevrolet Monte Carlo Cars & Trucks

2 Answers

1996 mazda pickup 4 cylinder and the heat doesnt work, there is antifreeze and the engine temp gage stays cool, but there is no heat? any suggestions?

try flushing the heater rad out with a garden hose ,another trick is to put a piece of cardboard in front of the radiator to increase engine temperature

Dec 05, 2010 | Mazda B2300 Cars & Trucks

4 Answers

Temperature gage does not show temp properly, gage jumps all over but engine is not overheated.

if the engine is not over heating then the gage is in need of replacing.

Nov 30, 2010 | 2005 Buick LeSabre

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