Fault codeP2457

MODERATE

Exhaust Gas Recirculation Cooling System Performance

What this code means

Exhaust Gas Recirculation Cooling System Performance.

P2457 is a generic code: it means the same thing on every make. P2457 belongs to family P24xx — Auxiliary emission controls. Its page explains how to read a code and groups all its codes by part.

Type of fault

The signal stays within its electrical limits, but its value is not plausible: it does not match what the control unit expects given the other sensors. The sensor may be drifting with age, but it may also be faithfully measuring a real mechanical problem — a leak, a blockage, an air leak. Replacing the sensor without checking does not always clear the fault.

Exhaust gas recirculation (EGR) valve

The EGR valve sends part of the exhaust gas back into the intake to lower combustion temperature and nitrogen oxide emissions. The control unit opens it according to load and checks its position with a sensor built into the valve.

What you notice

Stuck open: rough idle, stalling, black smoke on diesels. Stuck closed: often nothing but higher emissions and sometimes pinging on petrol engines.

How to check it

Soot is the classic cause: a clogged or seized valve. Check its connector, then the valve itself and its pipes. In Klaro, compare the commanded EGR with the EGR error: a large and persistent error means the valve does not follow its command.

Watch it live in Klaro

With an OBD2 adapter plugged in, these live readings show the part at work, when your car reports them:

Commanded EGR
Actual EGR position, valve 1
EGR error
Intake manifold pressure

What to do

Have it checked this week. The car remains usable, but the fault will not clear itself and will fail the roadworthiness test.

Clearing a code switches the light off but repairs nothing: if the fault remains, the code comes back. Clearing a fault code yourself →

How to read this code

PPowertrain
2standardised code
4Auxiliary emission controls
57P2457