Code
P1446
FIAT
P — Powertrain
Additive system fault
Views:
UK: 5
EN: 1
RU: 4
AI status
Completed
Completed
100%
Causes
- Low or empty additive (DEF/AdBlue) tank
- Contaminated or incorrect additive fluid
- Clogged or blocked additive lines, filter or injector/nozzle
- Failed additive dosing pump
- Faulty additive injector/valve or dosing solenoid
- Defective level, temperature or pressure sensor in additive circuit
Symptoms
- Malfunction Indicator Lamp (MIL) / Check Engine light illuminated
- Additive/AdBlue warning or service light on instrument cluster
- Possible reduced engine power or limp mode (manufacturer dependent)
- Inability to complete regeneration cycles or aftertreatment regeneration warnings
- Emissions test failure or poor exhaust odor from incorrect additive
- Possible DPF/FAP/NOx system warnings
What to check
- Read and record freeze-frame data and all stored DTCs using a capable scan tool
- Check additive tank level and condition of fluid (colour, contamination, crystals)
- Visually inspect additive tank, filler cap and plumbing for leaks or damage
- Inspect connectors, wiring harness and grounds for corrosion, pin damage or poor contact
- Check fuses/relays related to the additive dosing system
- Using scan tool, monitor additive-related live data (level, temperature, pump status, injector commands)
Signal parameters
- Additive tank level (%) or raw sensor value
- Additive temperature (°C)
- Pump supply voltage (V) and control signal
- Injector/dosing valve command (duty cycle / pulse width)
- Pump current draw (A) while operating
- Pressure or flow reading if available (kPa or l/min)
Diagnostic algorithm
- Connect a full-function diagnostic scanner, read all codes and freeze-frame data; save results. 2) Verify vehicle service information/TSBs for P1446 and related FIAT procedures. 3) Inspect additive fluid level and sample fluid for contamination or incorrect type; if low or contaminated, refill with approved additive. 4) Visually inspect tank, filler neck, hoses, filter and dosing injector for leaks, blockages or crystallization; clean or replace as required. 5) Check fuses/relays for the additive pump and control circuits; repair if faulty. 6) With connector(s) disconnected, check resistance and wiring continuity to pump, injector and sensors; repair wiring or connectors showing faults. 7) Command the pump/injector via the diagnostic tool and observe operation (voltage, current, audible run, flow). 8) If pump/injector fails bench or on-vehicle tests, replace component. 9) After repairs clear codes, perform forced regeneration or additive system relearn if required by procedure and verify no recurrence of P1446. 10) If fault persists, inspect additive ECU/module and CAN communication and consider module replacement following manufacturer guidance.
Likely causes
- Empty or very low additive tank
- Faulty dosing pump or injector (common mechanical failure)
- Clogged nozzle/lines from contamination or crystallized additive
- Corroded connector or damaged wiring to pump/injector
- Failed level sensor giving incorrect tank reading
Fault status
Status
The vehicle detected a malfunction in the aftertreatment additive dosing system. Emissions control may be impaired; continued operation without repair can cause increased emissions and possible restriction of engine performance. Have the additive system inspected and repaired. This code is an indicator for diagnostic investigation, not a confirmed component failure.
Repair difficulty: Medium
Diagnostic time: 1.5-3 hours
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