P0402

Code

LAND ROVER P — Powertrain

excessive exhaust gas recirculation flow detected

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 19 EN: 43 RU: 38

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Page language: EN

Causes

Stuck-open or mechanically binding EGR valve (electrical or vacuum type).
Faulty EGR position sensor or feedback sensor (DPFE/differential pressure sensor).
Leaking or over-actuating EGR vacuum solenoid or control valve.
Intake, EGR passages, or EGR cooler blockage or full-flow restriction causing erroneous sensor readings.
Vacuum leaks or boost/control system faults causing abnormal EGR operation (turbo applications).
Wiring harness faults: short to power/ground, poor connector, or damaged harness to EGR/DPFE/solenoid.

Symptoms

Malfunction Indicator Lamp (MIL/CEL) illuminated with P0402 stored.
Rough idle, hesitation or surging, especially at idle or low load.
Loss of power or poor throttle response under acceleration.
Black smoke or increased soot (diesel engines) and reduced fuel economy.
Stalling at idle or during deceleration in severe cases.
Failed emissions test/visible increase in tailpipe emissions.

What to check

Read and record freeze-frame and live data using a scan tool (EGR commanded vs actual, DPFE voltage, intake vacuum/MAP, RPM, MAF).
Perform visual inspection: EGR valve, solenoids, vacuum/boost hoses, wiring connectors and harness for damage or disconnection.
Check for diagnostic trouble codes related to EGR sensors, vacuum supply, MAF, MAP, or PCM communication.
Manually operate or command the EGR valve with a scan tool and observe movement and effect on engine (careful with hot components).
Smoke-test intake and vacuum lines for leaks (vacuum-operated systems).
Inspect EGR passages and cooler for heavy carbon build-up or restriction; inspect for internal leakage in EGR cooler.

Signal parameters

EGR commanded position (%) — commanded by PCM during test or various load conditions.
EGR actual position or position sensor voltage (V) — should correlate with commanded position.
DPFE/differential pressure sensor voltage or differential pressure (kPa) — indicates flow magnitude.
Intake manifold absolute pressure (MAP) / intake vacuum — abnormal values may indicate stuck-open EGR.
MAF (g/s) and engine RPM — changes when EGR is commanded (expect small transient changes).
O2 sensor / combustion quality — may show enrichment/rich conditions with excessive EGR.

Diagnostic algorithm

Retrieve freeze-frame and confirm P0402 and any related codes. Note engine temp, load, RPM at fault occurrence.
Clear codes and perform a road/drive cycle to see if code returns. If intermittent, focus on loose connections and hoses.
Visually inspect EGR valve, solenoids, vacuum/boost lines, connectors and wiring for damage, corrosion or disconnection.
With a scan tool, monitor commanded EGR vs actual position/DPFE while commanding the valve open/closed. Verify actual follows command (when safe to do so).
For vacuum EGRs: apply controlled vacuum to the valve and observe operation; check vacuum reservoir, vacuum solenoid, and check valve function.
For electrically actuated EGRs: bench-test or backprobe actuator and position sensor; verify correct voltages, resistance, and that actuator moves when commanded.
Test DPFE/differential pressure or EGR flow sensor: compare sensor voltages to manufacturer specs and verify there are no blocked passages giving false high readings.
Perform smoke test of intake and vacuum/boost systems to identify leaks that could alter EGR behavior.
Inspect and, if necessary, clean EGR valve, ports, and cooler. Remove carbon deposits that can prevent proper seating or create abnormal flow paths.
If components fail tests, replace the faulty EGR valve, solenoid, DPFE/sensors, or repair wiring as required. After repair, clear codes and re-test to ensure P0402 does not return.
If electrical tests are inconclusive and mechanical/EGR components check good, consider PCM software updates or replacement per factory bulletins.

Likely causes

EGR valve stuck partially/fully open (mechanical carbon buildup or failed actuator).
Faulty differential pressure/EGR feedback sensor giving high flow indication.
Defective EGR control solenoid or vacuum supply over-pressurizing the valve.
Leaks in vacuum/boost lines or clogged/incorrectly routed EGR passages.

Fault status

⚠️ Status

The PCM has detected more EGR flow than expected for current engine conditions. Excessive EGR can cause poor combustion, reduced performance, increased emissions, and drivability issues. Investigation should confirm whether the flow measurement is accurate or if the EGR system is malfunctioning.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5 - 3.0 hours