MotorBitP0402: EGR Flow Excessive Detected
Too much EGR flow, often a valve stuck open. Idle can be terrible.
Educational OBD2 information. Confirm on your vehicle with a scan tool. MotorBit can read this code, freeze frame, and live data over an ELM327 adapter.
What P0402 means
More exhaust was recirculated than the PCM commanded.
Why the check engine light comes on
Excess EGR dilutes the mixture too far, causing misfire and emissions failure.
Common causes
- EGR valve stuck open
- Carbon holding the valve off its seat
- Control circuit fault
Typical symptoms
- Rough idle
- Stalling
- Hesitation
What to do next
- Check EGR position at idle in live data — it should be closed.
- Clean or replace the valve.
How MotorBit helps
Open MotorBit, connect your ELM327, and read P0402 with freeze frame (RPM, load, temperature, speed at the moment the fault set). Then watch live PIDs and fuel trims instead of replacing parts by guesswork. When the repair is verified, clear the code and re-check monitors.
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FAQ
Is P0402 serious?
Severity is listed as medium on this page. Misfire, crank/cam, and communication codes deserve faster attention than a tiny EVAP leak.
Will disconnecting the battery clear P0402?
It may hide the lamp temporarily, but the fault usually returns and you lose freeze-frame evidence. Scan first, then clear after the repair.
Can MotorBit clear P0402?
Yes, after you understand the cause. Clearing without a repair is how the light comes back on the next drive cycle.