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Code

P0405

Emissions / EGR

EGR sensor A circuit low

The EGR position sensor signal is too low.

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Most likely causes

Faulty EGR position sensor
Wiring fault
Carbon in the valve

Symptoms you may notice

Check engine light
Rough idle

Checks to run

Test the position sensor
Clean the EGR
Check wiring

Tools you may need

Multimeter

Always diagnose before replacing. Codes share symptoms; confirm the cause with measurements before buying parts.

Related codes in Emissions / EGR

EGR flow insufficient

EGR circuit malfunction

EGR flow malfunction

EGR valve range / performance

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