P244D: Exhaust Temperature Too High For Particulate Filter Regeneration Bank 1
What to do
Stop driving hard and get this looked at promptly. The exhaust has run hot enough that the system aborted deliberately to avoid melting the filter, and the conditions that caused it have not gone away.
If you have been ignoring a particulate filter warning light, say so. It is the single most useful thing you can tell the garage here — a heavily loaded filter is the commonest reason temperature runs away, and knowing how long the light has been on tells them what to expect when they inspect it.
Avoid parking over long grass or anything flammable until it is repaired. An exhaust running at regeneration temperature is genuinely hot enough to be a fire risk, which is why some manufacturers warn about it explicitly.
Expect the filter itself to be inspected, not just the sensor. Asking whether it survived is a fair question, and the answer changes the cost of the job considerably.
What this code means
Exhaust temperature during a particulate filter regeneration has exceeded the safe limit, and the regeneration has been abandoned to protect the filter.
A regeneration is a controlled fire. Extra fuel raises exhaust temperature to somewhere around 600°C so that trapped soot burns away. The control is the important word — above roughly 800°C the ceramic substrate itself begins to melt, and a melted filter is a replacement.
The usual reason temperature runs away is that there was too much soot to burn. A filter that has been allowed to load heavily, then finally gets a regeneration, releases far more heat than the strategy expected. This is why an ignored particulate filter warning becomes an expensive repair — the warning asks for a drive that would have burned off a manageable amount.
The other explanations are worth checking in order.
- A faulty temperature sensor reporting high when the exhaust is not, which is the cheapest outcome.
- A leaking or stuck-open injector putting far more fuel into the cylinder than the regeneration strategy asked for.
- A post-injection or aftertreatment injector delivering too much fuel directly into the exhaust.
Do not simply clear this and continue. If the temperature genuinely reached the limit, the filter may already be damaged, and the next attempt starts from a filter that is still full.
Likely causes
Start here
- Genuine exhaust over-temperature during regeneration · specialist
- Particulate filter heavily loaded with soot · moderate
Less common
- Leaking fuel injector · specialist
- Faulty exhaust gas temperature sensor · moderate
- Excessive post-injection fuel quantity · specialist
Symptoms
Components involved
Information, not instruction
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