U0406: Invalid Data Received From Fuel Injector Control Module
What to do
Expect reduced power and possibly a limited rev range, along with rough running.
This module drives the injectors and reports back whether each injection actually happened as asked. When that report stops making sense, the engine deliberately holds back rather than fuelling on information it cannot verify — so the lack of power is protection.
The fault is often a single injector rather than the module. These modules report on each injector separately, and one shorted or open injector is enough to make the whole report unacceptable. Ask for the injectors and their wiring to be tested individually before the module is replaced.
Two other things worth raising. If injectors have been replaced recently, ask whether their calibration codes were programmed — see P2690, because uncoded injectors produce feedback that does not add up. And ask for the module's mounting and heat sink to be checked: these run hot, and unlike most modules on the car, heat damage is a genuine cause here.
What this code means
The fuel injector control module is broadcasting data that cannot be accepted as true. See U0400 for the family's framing.
A separate injector control module exists where the injectors need drive electronics the engine module cannot provide directly — most commonly on diesels with piezo injectors, which require high voltages and precisely shaped pulses, and on some engines with hydraulically actuated injection.
What it reports back is the substance of this code: confirmation that each injection actually happened as commanded — the timing achieved, the current delivered, and whether any channel faulted. The engine module needs that feedback because it is fuelling on the assumption that its commands were carried out.
An implausible report therefore breaks a loop that matters. The engine module cannot verify what was injected, and its response is to derate — reduced power, sometimes a limited rev range — because continuing to fuel confidently on unverified feedback is the thing it must not do.
As with the rest of this family, look past the module. Injector control modules report per-channel results, and a single shorted or open injector is enough to make the whole report unacceptable — which the corpus already describes as one injector dragging a driver down. So the fault is frequently one injector or its wiring, not the module.
One thing specific to these systems and worth asking about: heat. These modules dissipate real power and are often mounted on the engine or in the engine bay with a heat sink. A module that has been cooking gradually is a genuine failure mode here — unlike most of the modules in this family — so its mounting, its heat sink contact and any thermal paste are worth inspecting rather than assumed.
And the calibration point from P2690 applies: injectors carry individual codes, and a set fitted without them produces feedback the module cannot reconcile.
Likely causes
Start here
- Shorted injector dragging the driver down · moderate
- Failed injector control module · specialist
- Damaged injector wiring harness · moderate
- Heat damage to sensor or wiring · moderate
- Corroded or loose connector · easy
Less common
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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