What Is Fault Code SPN 1172 FMI 3? (Cummins)
Not every fault code will cause a derate. That is one of the good aspects of these fault codes. If you catch them early enough, you may never experience the troubling derate option many other owners have experienced. You may get an amber light but no mention of a derate.
The meaning of the code SPN 1172 is- Turbo Charger Compressor Inlet Temperature Circuit Failed High: Engine Turbocharger 1 Compressor Intake Temperature Voltage Above Normal, Or Shorted To High Source; Compressor Inlet Temperature Failed High. Only 7 repair steps to take.
To learn more about this fault code and others like it, just continue to read our article. It has the information you want to know about so you can take care of this problem as quickly as possible. Getting back on the road sooner rather than later is always the goal.
SPN 1172 FMI 3 Cummins
The good news is twofold. First, this code is number 691 on the complete Cummins fault code list. The J1939 description is - Engine Turbocharger 1 Compressor Intake Temperature. The Cummins description is a bit longer. It says:
“Turbocharger 1 Compressor Intake Temperature Circuit - Voltage above normal, or shorted to high source” That is basically the same as the official SPN fault code list.
The other piece of good news is that two more 1172 fault codes, FMI 2 & 4, appear right under this code. You do not have to search high and low to get an explanation for these codes.
The possible sources for this code are- an open circuit in the wiring harness, connectors, or sensor; an open signal circuit or there is a short to a voltage source; and finally, a damaged sensor.
There may be other codes that have been set at the same time. If these codes appear together,1172/3, 3250/3, 3242/3, and 3246/3, you need to go to step three in this repair guide.
If only the SPN 1172 FMI 3 code appears then you need to go to step 5 in the same repair guide. Your goal is to see that the voltage is less than 2.75, if not, you will be replacing parts.
SPN 1172 FMI 2
The Cummins equivalent to this fault code is 693 and its descriptions are as follows: “Engine Turbocharger 1 Compressor Intake Temperature
Turbocharger 1 Compressor Intake Temperature - Data erratic,
intermittent or incorrect.”
To fix this code, you have to do a Turbo Compressor Inlet Temperature Sensor Check. You do that by following these upcoming steps:
“1. Disconnect the Turbo Compressor Inlet Temperature Sensor.
2. Inspect the Turbo Compressor Inlet Temperature Sensor connectors for bent, damaged, or corroded pins.
[a] If damaged pins are found, repair them as necessary. Refer to section 84.1.1.1.
[b] If no damage is found, replace the Turbo Compressor Inlet Temperature Sensor.” (source)
That is all there is to repairing this fault code. We found no indication that your engine should derate but one owner did experience this problem and could not go above 25 mph. None of the data sheets we have looked at mentioned any derate being possible.
SPN 1172 FMI 4
The equivalent Cummins fault code number is 692 and its descriptions are- Engine Turbocharger 1 Compressor Intake Temperature Turbocharger 1 Compressor Intake Temperature Circuit - Voltage below normal, or shorted to low source.
In all three cases, you should only see an amber light illuminated on your dash. In checking other SPN 1172 FMI codes, not mentioned that the problem will reach a severe or even a moderately severe level.
One of the main repairs for this FMI code and FMI 2 is to make sure your ECM is calibrated properly. Three possible sources for this code are: a damaged sensor; a signal circuit shorted in the return or to ground in the sensor; and finally, signals circuit shorted to ground in the wire harness.
The repair for this problem is quite simple as well and the 4 steps you need to take go like this:
1. Turn the ignition OFF.
2. Disconnect the TCI Sensor.
3. Disconnect the 120–pin MCM connector.
4. Measure the resistance between pin 1 and pin 2 of the TCI Sensor Harness connector.
[a] If the resistance is less than 3 Ω, repair the short between pin 1 and pin 2 of the TCI
Sensor Harness connector and pin 86 and pin 88 of the 120–pin MCM connector.
Refer to section 84.3.1.1.
[b] If the resistance is greater than 3 Ω, repair the short to ground between pin 2 of the
TCI Sensor and pin 86 of the 120–pin MCM connector. Refer to section 84.3.1.1. (we already linked to this source above)
A Derate is Possible
There is a way for your engine to derate even though these codes do not indicate that a problem can happen. According to one mechanic, this is possible if your engine did not go through a complete regen.
But if you have done a DPF delete, then you should not see a derate at any time. However, if the problem is with the turbocharger, and it is not working correctly, you will see a loss of power to the engine.
The problem with the turbocharger may come from a damaged or malfunctioning 2-wire temperature sensor. This sensor is located in the air intake of the turbocharger.
Do not ignore the pressure sensor that is located in the intake manifold. This may be a source of your trouble as well. The pressure sensor has 3 wires and the intake manifold is on the driver’s side of the engine.
Some Final Words
This is not a difficult fault code to fix. Just follow the instructions given above and you should be able to clear the codes in no time at all. Just be careful though, you may end up replacing parts if a sensor or something else has malfunctioned.
You may also see SPN 1172 FMI 21 but there is no repair information currently available at this time. FMI 21 simply means the data drifted low.
