P2698: Exhaust Aftertreatment Fuel Injector A Performance
What to do
Two very different things produce this code, and what you can smell and feel tells them apart.
If there is a strong smell of unburnt diesel from the exhaust, unusual heat from under the vehicle, or a regeneration that seems to go on far longer or hotter than usual — stop and get it looked at. That points to the injector leaking fuel continuously into a hot exhaust, which can overheat and destroy the particulate filter and, in the worst case, is a fire risk. It is not something to continue driving on.
If instead the particulate filter warning keeps appearing and regenerations never seem to finish, that is the ordinary version: the nozzle has coked up with carbon and is not spraying properly. Less urgent, but it will block the filter eventually. Ask whether the nozzle tip and seal can be cleaned or replaced separately — on many vehicles they are a serviceable item and much cheaper than the whole injector.
Either way, mention any change in fuel consumption. A leaking injector shows up there before it shows up anywhere else.
What this code means
The exhaust fuel injector is electrically sound and is not delivering what the module commanded — too little, too much, or not when asked. What the injector is for is explained at P2697.
This is the code with a genuine hazard behind one of its readings, and it is worth separating the two.
Under-delivery is the common and unremarkable case. The injector sprays into the exhaust stream, which is the dirtiest environment available, so its nozzle cokes up — carbon builds on the tip until the spray pattern collapses into a dribble or stops. The consequence is a regeneration that never reaches temperature and a filter that loads progressively. On many vehicles the tip and its seal are a serviceable item, so cleaning or replacing the nozzle is a smaller job than replacing the injector.
Over-delivery is the case that matters. A nozzle that no longer seals passes fuel continuously rather than only when dosed, and raw diesel then enters a hot exhaust with no metering at all. Three things follow, in order of seriousness. Unburnt fuel reaching the particulate filter can raise its temperature far beyond the controlled range of a normal regeneration, which cracks or melts the substrate — turning a leaking injector into a filter replacement. Fuel that does not burn drips and accumulates. And an uncontrolled exothermic reaction in an exhaust system under a vehicle is a fire risk, which is why a strong smell of unburnt diesel from the exhaust, or a regeneration that seems unusually hot or unusually long, should be treated as a reason to stop rather than a curiosity.
The distinguishing evidence is available to the driver and worth reporting: a filter that will not regenerate points at under-delivery, while a fuel smell from the exhaust, unusual heat under the vehicle, or fuel consumption that has climbed with no change in driving points at a leaking injector.
This code is marked more serious than its neighbours for that second reading alone.
Likely causes
Start here
- Coked exhaust aftertreatment fuel injector · moderate
- Leaking exhaust aftertreatment fuel injector · moderate
- Faulty exhaust aftertreatment fuel injector · moderate
Less common
- Restricted fuel filter · easy
- Low fuel supply pressure · moderate
- Blocked diesel particulate filter · specialist
Symptoms
Components involved
Information, not instruction
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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.
Community experience
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