Success message
Error message
neutralNotificationMessage
Enter keywords above to find what you need.
Check your spelling or try different wording.
Hi, undefined
Already have an account?
Log In
We will send you an email to reset your password.
You'll receive an email shortly.
Tier 4 Final and Stage IV machines built on FPT NEF and Cursor engines run an SCR-only aftertreatment system: a diesel oxidation catalyst and an SCR catalyst, with no particulate filter and no exhaust gas recirculation. Everything the engine control unit knows about that system comes from six components - two NOx sensors, the NH3 sensor, the AdBlue quality sensor, the tank level and temperature sensors, and the Denoxtronic 2.2 dosing unit. When one of them reports a value the ECU does not accept, it logs a fault and starts the inducement countdown.
This section lists the codes those faults produce, what each one usually means, and what to check before replacing a part. It is a diagnostic reference. It does not describe how to clear or suppress a fault.
CNH machines show two things when an SCR fault is active. The dashboard displays a short numeric code, and the diagnostic tool reports a pair of numbers in the SAE J1939 format: an SPN and an FMI.
The SPN, or Suspect Parameter Number, says which component or measurement is at fault. SPN 3216 is the NOx sensor upstream of the SCR catalyst; SPN 3226 is the one downstream.
The FMI, or Failure Mode Identifier, says what kind of failure it is. The same SPN with a different FMI is a different problem: SPN 3216 FMI 5 is an open circuit at the upstream sensor, while SPN 3216 FMI 20 is the same sensor still connected but reading high.
Read them together. The SPN alone tells you where to look, not what to do.
These are the same across every J1939 machine, whatever the badge on the bonnet.
FMI 0 - Value above normal range, most severe
FMI 1 - Value below normal range, most severe
FMI 2 - Data erratic, intermittent or incorrect
FMI 3 - Voltage above normal, or shorted to a high source
FMI 4 - Voltage below normal, or shorted to a low source
FMI 5 - Current below normal, or open circuit
FMI 6 - Current above normal, or grounded circuit
FMI 7 - Mechanical system not responding correctly
FMI 9 - Abnormal update rate
FMI 10 - Abnormal rate of change
FMI 11 - Root cause not known
FMI 12 - Failed component or intelligent device
FMI 13 - Out of calibration
FMI 14 - Special instructions
FMI 15 - Value above normal range, least severe
FMI 16 - Value above normal range, moderately severe
FMI 17 - Value below normal range, least severe
FMI 18 - Value below normal range, moderately severe
FMI 19 - Network data received in error
FMI 20 - Data drifted high
FMI 21 - Data drifted low
FMI 31 - Condition exists
FMI 3, 4, 5 and 6 are wiring faults. Before ordering a sensor, check the connector and the loom.
FMI 20 and 21 mean the sensor is alive but drifting. That is ageing, contamination or an exhaust leak between the sensor and the catalyst — not always the sensor itself.
SPN 1761 - AdBlue tank level
SPN 3031 - AdBlue tank temperature
SPN 3216 - NOx sensor, upstream of the SCR catalyst
SPN 3226 - NOx sensor, downstream of the SCR catalyst
SPN 3361 - AdBlue dosing unit
SPN 3364 - AdBlue quality and concentration
SPN 4094 - NOx limit exceeded, insufficient reagent quality
SPN 4095 - NOx limit exceeded, dosing interrupted
SPN 4334 - AdBlue dosing pressure
SPN 4360 - SCR catalyst inlet temperature
SPN 4363 - SCR catalyst outlet temperature
SPN 4364 - SCR conversion efficiency
SPN 5394 - AdBlue doser valve
The numbers follow SAE J1939. The wording a manufacturer prints on the dashboard may differ from the descriptions above, and some machines add codes of their own outside the standard range.
The two most common SCR faults on this platform, and the two most often replaced unnecessarily.
Both sensors sit in the exhaust and both are on the CAN bus. Their heating elements draw current and their ceramic elements age. An open circuit, FMI 5, is usually the connector rather than the sensor - heat cycling and vibration work the pins loose, and the loom runs through the hottest part of the machine. A drifting reading, FMI 20 or 21, is different. A downstream sensor reading high is often not a sensor problem at all: it can mean the catalyst genuinely is not converting, which points back at the dosing side.
The quality sensor measures urea concentration, which should be 32.5 per cent. Anything meaningfully outside that window logs a fault.
The usual cause is not the sensor. AdBlue degrades - above roughly 30 °C it loses concentration over a matter of months, and a container left open in a yard through a summer will drift out of specification on its own. Dilution with water, whether accidental or deliberate, does the same thing faster.
The Denoxtronic 2.2 pump has to build and hold pressure, and the doser valve has to open into a hot exhaust and close cleanly.
Crystallisation is the dominant failure. Urea deposits build up at the injector tip and inside the dosing line, restricting flow until the pump cannot reach commanded pressure. A pressure fault, SPN 4334, is very often a blockage rather than a failed pump.
The pump also runs a purge cycle at shutdown to clear the line. If the machine is switched off at the battery isolator before that cycle completes — which happens constantly in practice — fluid stays in the line and crystallises. Repeated over a season, that alone will produce a dosing fault.
This is not a component fault. It is the ECU comparing the upstream and downstream NOx readings and concluding that not enough NOx is being converted.
It has four possible causes, and the code itself does not distinguish between them: the catalyst is not receiving enough AdBlue, the AdBlue is out of specification, the catalyst itself is degraded or contaminated, or one of the NOx sensors is lying.
These two are not diagnoses. They are the ECU recording why it started restricting the machine - insufficient reagent quality, or interrupted dosing. They appear alongside the fault that caused them.
If one of these is active without an obvious partner code, the underlying fault may have been intermittent and gone inactive while the inducement counter kept running.
Inducement on Tier 4 Final and Stage IV machines runs in stages, and the stages are set by regulation rather than by the manufacturer.
The dashboard warns first. If the fault is not repaired, the ECU reduces available torque. If it is still not repaired, engine speed is limited and the machine is left able to move but not to work.
The counter does not reset when the warning is acknowledged. It resets when the fault is repaired and the ECU sees a valid signal again.
This is why an SCR fault takes a machine out of service rather than merely inconveniencing it, and why the timing matters: a fault logged at the start of harvest and a replacement pump quoted at two to three weeks are the same problem.
Diagnosing the fault does not put the machine back to work if the replacement part is three weeks out.
The Lavanis SCR-One is a repair-support tool for exactly that gap. It is fitted while the correct part is on order, it requires no ECU programming and no change to the wiring, and it is removed before the OEM repair is carried out.
It does not repair the SCR system and it is not a substitute for OEM service. It keeps the machine working until the repair can be done.