Faulty or contaminated NOx sensor located downstream of the SCR catalyst, providing an erroneous high-temperature reading.; Excessive diesel exhaust fluid (DEF) injection due to a sticking or leaking DEF injector, or a faulty dosing control module.; Restricted or damaged SCR catalyst causing hot spots and elevated outlet temperatures.; Exhaust gas recirculation (EGR) system malfunction leading to high exhaust temperatures entering the SCR system.; Wiring or connector issues (corrosion, chafing, open circuit) in the NOx sensor circuit.; Software calibration error in the powertrain control module (PCM) requiring an update.; Engine overheating or other base engine faults that raise exhaust temperatures beyond normal ranges.

DTC codes / P21xx · Fuel and air metering / P214C

P214CSCR NOx Catalyst Outlet Temperature Too High

Q: What does code P214C mean?

SCR NOx Catalyst Outlet Temperature Too High. P214C indicates that the powertrain control module has detected an excessively high temperature at the outlet of the selective catalytic reduction (SCR) NOx catalyst, which is part of the diesel exhaust aftertreatment system. The computer compares the outlet temperature sensor reading against expected values and sets this code when the temperature exceeds a calibrated threshold, often due to a fault in the dosing or sensor system.

P214C indicates that the powertrain control module has detected an excessively high temperature at the outlet of the selective catalytic reduction (SCR) NOx catalyst, which is part of the diesel exhaust aftertreatment system. The computer compares the outlet temperature sensor reading against expected values and sets this code when the temperature exceeds a calibrated threshold, often due to a fault in the dosing or sensor system.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaFuel and air metering

Symptoms you may notice

Illumination of the malfunction indicator lamp (check engine light), often with no other noticeable symptoms.
Reduced engine power or limp mode may be activated to protect the exhaust system.
Possible black or white smoke from the exhaust if the issue is related to excessive fuel or DEF injection.
A burning or chemical smell from the exhaust, especially after heavy load or regeneration.
Increased diesel exhaust fluid (DEF) consumption if the cause is over-dosing.
In rare cases, the driver may notice a hesitation or rough running if the engine management is intervening.

Common causes, most likely first

Faulty or contaminated NOx sensor located downstream of the SCR catalyst, providing an erroneous high-temperature reading.
Excessive diesel exhaust fluid (DEF) injection due to a sticking or leaking DEF injector, or a faulty dosing control module.
Restricted or damaged SCR catalyst causing hot spots and elevated outlet temperatures.
Exhaust gas recirculation (EGR) system malfunction leading to high exhaust temperatures entering the SCR system.
Wiring or connector issues (corrosion, chafing, open circuit) in the NOx sensor circuit.
Software calibration error in the powertrain control module (PCM) requiring an update.
Engine overheating or other base engine faults that raise exhaust temperatures beyond normal ranges.

How to diagnose and fix it

Use a scan tool to verify the code and check for any related pending or stored codes, then record freeze-frame data.
Visually inspect the NOx sensor, its wiring, and connectors for damage, corrosion, or loose connections; repair as needed.
Check the DEF injector for leaks or signs of excessive dosing, and perform an injector quantity test if supported by the scan tool.
Monitor live data for the SCR outlet temperature sensor and compare with actual exhaust temperatures using an infrared thermometer to validate the sensor reading.
Inspect the SCR catalyst for restrictions or damage, and perform a backpressure test if applicable.
Check for technical service bulletins (TSBs) or software updates for the PCM that address this code.
If all else fails, follow the manufacturer's diagnostic flow chart, which may involve replacing the NOx sensor or SCR catalyst after confirming the root cause.

Don't jump to replacing the SCR catalyst

A common misdiagnosis is to replace the SCR catalyst when the real fault is a skewed NOx sensor; always validate sensor readings with an independent temperature measurement before condemning the catalyst.
Excessive DEF injection from a sticking injector can cause the outlet temperature to spike without any sensor fault, so inspect the injector spray pattern and dosing quantity.
The code can be set by a one-time event such as a failed regeneration or a long uphill pull, and may not indicate a hard failure; check freeze-frame data for conditions at the time of setting.
Wiring harness damage near the exhaust system is frequent due to heat and vibration, so perform a thorough continuity and resistance test on the sensor circuit.
On some vehicles, a faulty exhaust gas temperature sensor upstream of the SCR can cause the system to overcompensate and raise outlet temperatures, so scan all temperature sensor values for plausibility.

Can I keep driving with P214C?

It is generally safe to drive with this code as long as the engine is not in limp mode and no other severe symptoms are present, but avoid heavy loads and prolonged high-speed driving until diagnosed. Continued driving with excessively high SCR temperatures can lead to catalyst damage and more expensive repairs, so schedule a diagnostic appointment soon.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.