Faulty exhaust gas temperature sensor at the SCR catalyst inlet, sending a high reading; Excessive diesel exhaust fluid injection due to a stuck-open dosing valve or faulty injector; Restricted or failed SCR catalyst causing a temperature rise from trapped hydrocarbons; Engine over-fueling or misfire sending unburned fuel into the exhaust and raising temperatures; Wiring damage or corrosion in the SCR temperature sensor circuit causing a skewed signal; Software calibration error in the ECM affecting SCR temperature management

DTC codes / P21xx · Fuel and air metering / P214A

P214ASCR NOx Catalyst Inlet Temperature Too High

Q: What does code P214A mean?

SCR NOx Catalyst Inlet Temperature Too High. P214A means the engine control module has detected that the exhaust gas temperature at the inlet of the selective catalytic reduction (SCR) catalyst is higher than the calibrated safe limit. The SCR system uses diesel exhaust fluid to convert nitrogen oxides into harmless gases, and excessive inlet temperature can damage the catalyst or indicate a fault in the dosing or temperature sensing circuit.

P214A means the engine control module has detected that the exhaust gas temperature at the inlet of the selective catalytic reduction (SCR) catalyst is higher than the calibrated safe limit. The SCR system uses diesel exhaust fluid to convert nitrogen oxides into harmless gases, and excessive inlet temperature can damage the catalyst or indicate a fault in the dosing or temperature sensing circuit.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyProfessional

AreaFuel and air metering

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Reduced engine power or limp mode triggered by the ECM to protect the SCR catalyst
A message on the dashboard indicating exhaust system service required or SCR system fault
Possible increase in diesel exhaust fluid consumption if the system is over-dosing to cool the catalyst
In rare cases, a burning or acrid smell from the exhaust if the catalyst is overheating

Common causes, most likely first

Faulty exhaust gas temperature sensor at the SCR catalyst inlet, sending a high reading
Excessive diesel exhaust fluid injection due to a stuck-open dosing valve or faulty injector
Restricted or failed SCR catalyst causing a temperature rise from trapped hydrocarbons
Engine over-fueling or misfire sending unburned fuel into the exhaust and raising temperatures
Wiring damage or corrosion in the SCR temperature sensor circuit causing a skewed signal
Software calibration error in the ECM affecting SCR temperature management

How to diagnose and fix it

Use a scan tool to read live data from the SCR inlet temperature sensor and compare it to actual exhaust temperature with an infrared thermometer
Inspect the sensor wiring and connector for chafing, corrosion, or loose pins, and repair as needed
Test the SCR dosing valve for proper operation and check for excessive DEF injection or leaks
Check for engine performance faults such as misfires or fuel injector issues that could raise exhaust temperatures
Perform a visual inspection of the SCR catalyst for damage, blockage, or contamination
Verify ECM software is up to date and reflash if a known calibration issue exists
Replace the faulty temperature sensor or dosing valve only after confirming the diagnosis with live data

Don't overlook the dosing valve

A common misdiagnosis is replacing the SCR catalyst when the real cause is a leaking or stuck-open DEF dosing valve that over-injects fluid and artificially raises inlet temperature.
The code can be set by a faulty temperature sensor that reads high even when actual exhaust temperatures are normal, so always cross-check with an infrared thermometer before condemning the catalyst.
Exhaust backpressure from a partially clogged diesel particulate filter can cause elevated SCR inlet temperatures, so check for related DPF codes and pressure readings.
Some vehicles set P214A after a low-speed, high-load driving cycle that temporarily exceeds temperature limits, and the code may not return if the driving pattern changes.
A weak or failing battery can cause voltage spikes that corrupt sensor signals, leading to false high-temperature readings, so check charging system health first.

Can I keep driving with P214A?

You can usually drive the vehicle for a short distance to a repair shop, but avoid heavy loads or sustained high-speed driving that could raise exhaust temperatures further. If the engine enters limp mode or you notice performance loss, stop driving and seek professional diagnosis to prevent catalyst damage.

Tools that help

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