The fault code P1445 on Peugeot indicates that the engine control unit has recorded an amount of FAP additive deemed too high. This fault affects HDi and BlueHDi diesel engines equipped with the Eolys additive system. It frequently appears after filling the additive reservoir, even when the operation has been performed correctly.
Theoretical counter of the control unit: the mechanism that the mechanic does not always reset
The engine control unit does not directly measure the level of additive in the tank. It calculates a theoretical injected quantity based on the number of fuel fills and the regeneration cycles of the particulate filter. This operation explains why a simple filling of the additive is not enough to turn off the warning light.
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On recent control units (Euro 6c/6d), according to technical notes relayed by Diagoss trainers in 2024, an additive fill performed too early relative to the internal counter triggers the P1445. The control unit considers that the maximum dose has been reached and blocks the regenerations of the FAP, even if the filter is not clogged.
Before looking for a hardware fault, the first check is therefore on the consistency between the actual level of additive and the value recorded by the control unit. To learn everything about the P1445 Peugeot code and common mistakes after a fill-up, resetting the additive counter via a diagnostic tool is the mandatory starting point.
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FAP ash counter and code P1445: the forgotten double reset
The additive counter is not the only parameter to reset. BlueHDi engines also have a FAP ash counter that records the accumulation of combustion residues in the particulate filter. This counter follows a separate logic.
Practical cases compiled by ACTIA Academy (training “PSA Additized FAP Diagnosis”, updated 2023) and published in Autotechnica magazine show a recurring scenario: the P1445 reappears after a correct filling of the additive because the ash counter has not been reset. The control unit then considers the FAP to be at the end of its life and maintains the blockage of regenerations, even after cleaning or replacing the filter.
The complete procedure therefore requires a double reset via the diagnostic tool:
- Resetting the injected additive quantity counter, to inform the control unit that the tank has been correctly filled
- Resetting the FAP ash counter, to lift the end-of-life lock on the particulate filter
- Checking the recorded mileage for the last fill-up, as a too large discrepancy between the actual mileage and the stored value skews the injection calculation
A generic diagnostic tool (type ELM327) often allows reading the P1445 code, but not always accessing specific PSA counters. A tool compatible with the manufacturer protocol (Diagbox, Lexia, or equivalent) is necessary for this operation.
Additive pump and additive circuit: when the problem is hardware
If the P1445 persists after the double reset, the hardware track becomes relevant. The additive circuit includes a dedicated tank (usually located under the vehicle), an electric pump, and pipes that transport the additive to the fuel.
Defective additive pump
The additive pump can fail without immediate symptoms. The control unit continues to count theoretical injections while no additive actually reaches the fuel. The FAP gradually becomes clogged, and the P1445 code eventually appears when the control unit reaches the programmed maximum threshold.
A pump functionality test is performed via the diagnostic tool by initiating a forced activation. If the pump does not respond, its replacement is the only option.
Leaks and blockages in the circuit
Additive pipes, exposed under the chassis, can become clogged due to Eolys crystallization or crack over time. A leak leads to an actual level lower than what the control unit estimates, gradually shifting all regeneration parameters.
Driving with an active P1445: the concrete consequences on the FAP and emissions
The P1445 does not lead to an immediate failure. The engine runs, the vehicle drives. This absence of a glaring symptom leads many drivers to postpone intervention. However, the consequences worsen over time.
When the control unit blocks regenerations, soot accumulates in the particulate filter. The exhaust back pressure increases, causing a gradual loss of power and increased fuel consumption. The entry into degraded mode occurs at an advanced stage, sometimes after several thousand kilometers.
A note from ADEME published in 2022 on additized FAP systems indicates that driving for a long time with the additive cut off and incomplete regenerations increases ultrafine particle emissions during accelerations. Beyond the mechanical aspect, the situation has a direct impact on the vehicle’s anti-pollution compliance, particularly during the technical inspection.
- A FAP clogged beyond a certain threshold can no longer be cleaned and must be replaced, which represents a cost significantly higher than a simple filling of additive with reset
- The degraded mode limits speed and engine RPM, making the vehicle difficult to use on the highway
- An unresolved FAP fault leads to a re-inspection during the technical control due to the strengthening of anti-pollution standards
The P1445 code after an additive fill remains in most cases a software parameterization issue, not a defective part. The double reset of the additive and FAP ash counters, performed with a diagnostic tool suitable for the PSA protocol, resolves the fault without part replacement. Postponing the intervention turns a software problem into an expensive mechanical failure.