P214D: SCR NOx Catalyst Outlet Temperature Too High During Particulate Filter Regeneration
What to do
Take this more seriously than it sounds, because the damage lands somewhere else. Every time this happens the emissions catalyst downstream loses a little capability permanently — so a vehicle that keeps doing it develops expensive SCR faults months later, and nobody connects the two.
If you have been ignoring a particulate filter warning, say so. A heavily loaded filter releases far more heat when it finally burns, which is the commonest reason the temperature runs away.
Ask for the exhaust fuel injector to be checked. A leaking one adds heat nobody asked for, and that is the version of this fault that keeps happening until it is fixed.
Expect regenerations to be aborted, which means the filter will keep loading — so this tends to make itself worse if left.
What this code means
The SCR catalyst got too hot while the particulate filter was regenerating.
This is a cross-system code, and the conflict it describes is built into the exhaust layout. A particulate filter regeneration is a deliberate fire — extra fuel raises exhaust temperature to around 600°C to burn accumulated soot away. An SCR catalyst is a chemical coating that is damaged by heat, losing activity permanently somewhere above 700 to 800°C.
On any vehicle where the SCR catalyst sits downstream of the particulate filter, one system's normal operation threatens the other. The module therefore watches SCR outlet temperature throughout a regeneration and aborts the regeneration if it climbs too far.
So this code is a protection event, and the question is why the temperature ran away.
- Too much fuel reaching the exhaust. A leaking or stuck-open aftertreatment injector adds heat nobody commanded — and that is the dangerous version, because it can keep adding it.
- A heavily loaded filter. More soot means more heat released when it finally burns, which is why an ignored filter warning becomes an expensive problem two systems away.
- A temperature sensor reading high, in which case nothing was ever too hot.
The damage is cumulative and silent. Each over-temperature event costs the catalyst some conversion capacity permanently, so a vehicle that does this repeatedly develops SCR efficiency faults months later with no obvious link back.
Likely causes
Start here
- Leaking exhaust aftertreatment fuel injector · moderate
- Particulate filter heavily loaded with soot · moderate
Less common
- Faulty exhaust gas temperature sensor · moderate
- Excessive post-injection fuel quantity · specialist
- Aged or contaminated SCR catalyst · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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