P2690: Cylinder 5 Injector Data Incompatible
What to do
If this appeared after injector work, nothing is broken — a step was missed.
Every modern diesel injector is individually flow-tested when it is made, and its own correction code is printed on it. That code has to be typed into the engine module against the exact cylinder the injector went into. It is part of the job, it takes a scan tool, and nothing about fitting the injector does it by itself.
Expect uneven idle, a harder knock from one cylinder, some smoke and worse economy meanwhile. You may also get a misfire code for the same cylinder, which unhelpfully points back at the injector that was just fitted — so it is easy to conclude the new part is faulty when the real answer is that it has not been coded.
Go back to whoever did the work and ask specifically whether the injector calibration codes were programmed, and whether they were entered against the right cylinders. If a set was fitted, two codes transposed leaves two cylinders both wrong.
Worth doing promptly rather than living with. An uncorrected injector may be putting more fuel into that cylinder than the engine intends, on every mile you drive, and that is hard on the piston over time.
What this code means
The calibration data the module holds for cylinder 5's injector does not match the injector actually fitted there — or there is none.
Nothing is broken. This code says a step in a repair was not completed, and reading it as a failure is what makes it expensive.
Why an injector needs data at all is the thing worth understanding. A common-rail injector opens for a fraction of a millisecond and delivers, on a pilot injection, a few cubic millimetres of fuel — a droplet. At that scale the manufacturing tolerances of the nozzle, the needle and the solenoid are not negligible; two injectors built on the same line to the same drawing deliver measurably different quantities for the same command. Rather than build that difference out, which would be ruinously expensive, each injector is flow-tested at manufacture and its individual deviation is encoded as a calibration code printed on its body — a short alphanumeric string, sometimes a data-matrix square.
That code has to be typed into the module against the cylinder the injector is fitted to. It is a step in the job, done with a scan tool, and nothing about fitting the injector does it automatically.
So the causes are all human rather than mechanical, and they are worth knowing in order:
- An injector fitted and never coded. The commonest by a wide margin.
- The code entered against the wrong cylinder. Fitting a set of injectors means entering several long strings in sequence, and one pair transposed leaves two cylinders each corrected by the other's data.
- A transcription error. These strings are long, printed small, on a part covered in diesel and often already fitted where the label is hard to read. A mistyped code is the worst version of this fault, because it may be accepted as valid and produce no code at all — just an engine that runs slightly wrong for ever afterwards.
- Injectors swapped between cylinders during diagnosis. Moving an injector to another cylinder to see whether a symptom follows it is a legitimate test — but the coding must move with it, and putting them back without re-coding leaves every cylinder wrong.
- A module replaced or reprogrammed, taking the stored codes with it.
- Second-hand injectors whose calibration codes are unknown or unreadable.
What it feels like: uneven idle, a harder knocking note from the affected cylinder, smoke, worse economy, and often a misfire code for the same cylinder that sends attention back to the injector that was just replaced.
It is worth fixing rather than living with, and not only for refinement. An uncorrected injector over-delivering puts more fuel into one cylinder than the module believes it has — a hotter, higher-pressure combustion in that cylinder alone, sustained over every mile driven. That is a slow risk to the piston and valves rather than an immediate one, but it is real.
One numbering note that will save a fruitless search. The standard assigns these per cylinder, and cylinders 1 to 4 are covered by codes in the letter-suffixed part of the P268x range rather than by decimal numbers — so a reader whose scan tool reports an injector data fault on cylinder 2 will not find it between P2690 and P2695. The decimal numbers here begin at cylinder 5.
Likely causes
Start here
- Injector fitted without entering its calibration code · specialist
- Injector calibration code entered incorrectly · specialist
Less common
- Injectors swapped between cylinders · specialist
- Engine control module replaced or reprogrammed · specialist
- Interrupted module programming · specialist
- Degraded module memory · 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.
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