Code
P1402
ALFA ROMEO
P — Powertrain
Flap fault | EGR throttle valve fault
Views:
UK: 3
EN: 9
RU: 8
AI status
Completed
Completed
100%
Causes
- Carbon/soot build-up restricting flap movement
- Faulty EGR throttle motor/actuator
- Faulty EGR flap/position sensor (potentiometer/Hall sensor)
- Open/short or corroded wiring/connectors to actuator or sensor
- Vacuum supply problem (if vacuum-actuated)
- Mechanical damage or seized linkage
Symptoms
- Check Engine Light (MIL) illuminated
- Rough idle, hesitation or poor driveability
- Reduced engine power or limp-home behaviour
- Increased emissions or failed emissions test
- Poor fuel economy
- Intermittent stalling at idle or low speed
What to check
- Read DTCs and freeze frame data with a capable scan tool (manufacturer-specific codes)
- Check for related EGR or intake system codes (P040x family)
- Visual inspection for carbon build-up, broken linkages, damaged wiring and connectors
- Monitor commanded vs actual EGR flap/position values and compare while commanding EGR
- Check power and ground to actuator and position sensor
- Measure sensor output voltage or resistance and compare to spec
Signal parameters
- Commanded flap position (degrees or %)
- Actual flap/position sensor reading (degrees or %)
- Acceptable commanded vs actual deviation: typically within ~5–15% (manufacturer-specific)
- Position sensor voltage range (typical 0.5–4.5 V for potentiometer-type)
- Actuator supply voltage (usually battery voltage when commanded) and ground continuity
- Actuator current draw when moving (abnormally high may indicate seizure or binding)
Diagnostic algorithm
- Retrieve P1402 and any related codes; record freeze frame (RPM, load, temp).
- Clear codes and attempt to re-run while monitoring live data (EGR command vs actual).
- Perform a visual inspection of EGR throttle and intake for heavy carbon deposits or seized linkage.
- With ignition on (engine off) verify position sensor output voltage and move flap manually (if safe) to observe sensor change.
- Command the EGR flap open/close using a scan tool and observe actual movement and response times.
- Verify power and ground at the actuator connector while commanding movement; check for wiring continuity and corrosion.
- If actuator receives proper voltage but does not move, remove and bench-test or replace actuator/module.
- If actuator moves but position feedback is out of range or inconsistent, test/replace position sensor or EGR throttle assembly.
- Clean carbon and deposits from valve, flap and passages if binding is present; reassemble and retest.
- After repair or replacement, clear codes, perform functional tests and road-test to confirm fault does not return. Consider dealer software update/TSB for known faults.
Likely causes
- Carbon accumulation jamming the flap or linkage
- Failed actuator that cannot move the flap or meet commanded position
- Position sensor out of range or sending incorrect voltage/position signal
- Wiring or connector fault between ECU and EGR throttle assembly
Fault status
Status
P1402 — EGR throttle valve/flap fault detected (flap position or operation out of expected range).
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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