P22FF: SCR NOx Catalyst Inlet Temperature Too Low

Diesel engines raise exhaust temperature on purpose so the SCR catalyst can reduce NOx; this code reports that the gas entering the SCR stays too cold despite that. Ford describes it for the 6.7L and 3.2L diesels under its monitoring of the exhaust temperature controller: the measured SCR inlet value is compared with the setpoint, and the fault sets when it lags more than 80 °C behind for 300 s (2015 model year, roughly 800-1600 rpm and 50-600 Nm, EGT and EGR inputs fault-free). Deutz EMR5 maps P22FF to SPN 4360 FMI 1, below the normal range. Volvo cut false P22FF settings with a 2021 engine software update (KC-589). P05EB covers cold starts, P214A the opposite case.

Symptoms

• Check engine light on
• Reduced NOx conversion, possible further SCR efficiency codes
• Code returns after extended idling

Most likely causes

• Long idling or light-load operation keeps exhaust cold
• Exhaust leak ahead of the SCR cools the gas or skews the reading
• Exhaust temperature sensor reading too low while still in range
• Engine software with overly strict monitor (update available on some makes)

What to check, in order

Start with the simplest. You can tick off each step.

1. Read the codes and the NOx data before and after the SCR catalyst
2. With the connector unplugged, check whether the signal wire is making contact with ground.
3. Check the sensor's connector and wiring
4. Look for exhaust leaks ahead of the sensor
5. Confirm that the AdBlue/DEF is of good quality
6. Replace the sensor only after ruling out power, ground, and leaks

Good to know

• Repair difficulty: medium
• It affects emissions.

What each character of P22FF means

• P: Powertrain: engine and transmission
• 2: Generic code: same on every make
• 2: Fuel injection
• FF: Specific fault in that system

Frequently asked questions

Can I keep driving with code P22FF?

You can usually keep driving in the short term, but get it repaired soon: on many diesels, the warning eventually limits starting or engine power.

What causes code P22FF?

The most common causes are: long idling or light-load operation keeps exhaust cold; exhaust leak ahead of the SCR cools the gas or skews the reading; exhaust temperature sensor reading too low while still in range.

Related codes

• P05EBCold Start SCR NOx Catalyst Inlet Temperature Too Low
• P214ASCR NOx Catalyst Inlet Temperature Too High
• P20EESCR NOx Catalyst Efficiency Below Threshold (Bank 1)
• P2080Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 1)
• P2084Exhaust Gas Temperature Sensor Circuit Range/Performance (Bank 1 Sensor 2)
• P249CExcessive Time To Enter Closed Loop Reductant Injection Control

Sources

• fordservicecontent.com: DOBDSM1501
• fordservicecontent.com: DOBDSM1301
• serdia.deutz.com: DTCList MD1 DE EN
• static.nhtsa.gov: MC 10210984 0001

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.