What are the symptoms of P0402?

Common symptoms include: Rough or surging idle; Hesitation; Smoke.

What causes a P0402 code?

The most common causes are: EGR valve stuck open; DPFE / EGR sensor fault; Carbon holding the valve open.

How do you fix P0402?

Inspect the EGR valve for stuck-open carbon; Test the EGR position/flow sensor; Clean or replace the valve. Worth diagnosing soon — left alone, the underlying issue can grow into a bigger, costlier problem.

OBD-II Code Lookup

P0402Watch

EGR Flow Excessive Detected

Emissions system

More exhaust is recirculating than commanded — often a valve stuck open or a sensor misreading flow.

Worth diagnosing soon — left alone, the underlying issue can grow into a bigger, costlier problem.

Common symptoms

Rough or surging idle
Hesitation
Smoke

Common causes

EGR valve stuck open
DPFE / EGR sensor fault
Carbon holding the valve open

How it's diagnosed & fixed

Inspect the EGR valve for stuck-open carbon
Test the EGR position/flow sensor
Clean or replace the valve

Got P0402? Get it diagnosed.

A real technician can interpret P0402 in the context of your truck and symptoms — and tell you what's actually wrong before you buy parts.

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Related Emissions codes

P0401EGR Flow Insufficient Detected P0404EGR Control Circuit Range/Performance P0420Catalyst System Efficiency Below Threshold (Bank 1)P0470Exhaust Pressure Sensor Fault

Reference only. A trouble code names a symptom, not the failed part — always confirm with a live diagnosis before repairs. See our Knowledge Base for deeper guides.