Cause
Emissions system tampering detected
The module concluding that emissions equipment has been removed, disabled or defeated. It is a finding rather than a fault, and it is recorded here because the codes are real and a diagnosis that does not know the vehicle has been modified will chase components that are no longer fitted.
Modern systems detect it several ways — a sensor reporting values impossible for a working component, a filter showing no pressure difference at all, a reductant system consuming nothing, or a calibration that does not match its signed reference. A differential pressure of near zero across a filter at all loads means there is no filter there, which is a stronger conclusion than any single code.
The practical position is worth stating plainly. In most jurisdictions removing or defeating emissions equipment makes a vehicle illegal for road use and will fail its test, and reinstating it is the only repair. Establish what has been done before quoting anything — the hardware, the software or both may have been changed, and a vehicle running a map written for absent equipment will run badly if the hardware is restored without the calibration.
Typically specialist work. Needs equipment or training most home workshops do not have.
Some of these codes mean you should stop driving
1 of the 3 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (3)
Codes where this is a likely explanation first, rather than merely a possible one.
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.
Others who found this
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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