P2457 Exhaust Gas Recirculation Cooling System Performance
OBD2 Error Codes

P2457 Exhaust Gas Recirculation Cooling System Performance

P2457 Exhaust Gas Recirculation Cooling System Performance

OBD-II DTC Datasheet

Exhaust Gas Recirculation Cooling System Features

What does this mean?

This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to all vehicles since 1996 (Ford, Dodge, GMC, Chevrolet, Mercedes, VW, etc.). Although general in nature, the specific repair steps may differ depending on the brand / model.

If your OBD-II equipped vehicle displays code P2457, it means that the powertrain control module (PCM) has detected a possible malfunction in the exhaust gas recirculation (EGR) cooling system. This could be a mechanical problem or an electrical problem.

The EGR system is responsible for delivering some of the exhaust gas back to the intake manifold so that it can be burned a second time. This process is necessary to reduce the amount of nitrogen oxide (NOx) particles emitted to the atmosphere. NOx contributes to exhaust gas emissions that deplete the ozone layer.

The need for EGR cooling systems is limited (as far as I know) to diesel vehicles. The engine coolant is used to reduce the temperature of the engine exhaust gases before they enter the EGR valve. The exhaust gas recirculation temperature sensor informs the PCM of changes in the exhaust gas temperature near the exhaust gas recirculation valve. The PCM compares the inputs from the EGR temperature sensor and the optional exhaust gas temperature sensor to determine if the EGR cooling system is operating effectively.

An exhaust gas recirculation cooler usually resembles a small radiator (or heater core) with fins on the outside, coolant inlet and outlet, and one or more exhaust pipes or pipes running through the center. Air flows through the fins to reduce the temperature of both the coolant (flowing through the outside diameter of the cooler) and the exhaust (flowing through the center of the cooler).

An additional exhaust gas temperature sensor is usually located in the downpipe and the exhaust gas recirculation temperature sensor is located next to the exhaust gas recirculation valve. If the EGR temperature sensor input is not within the programmed specifications, or if the EGR sensor input is not much lower than the auxiliary exhaust gas temperature sensor, P2457 will be stored and the malfunction indicator light may illuminate.

Symptoms and severity

Since P2457 is related to an exhaust emission system, this is not considered a flash code. Symptoms of a P2457 code may include:

  • When this code is stored, there may be no symptoms
  • Reduced fuel efficiency
  • Stored code
  • Illumination of the control lamp of malfunction
  • Leaking coolant
  • Exhaust gas leak
  • Exhaust Gas Temperature Sensor Codes


Possible reasons for setting this code:

  • Low engine coolant level
  • Exhaust gas recirculation temperature sensor defective
  • Defective exhaust gas temperature sensor
  • Exhaust leaks
  • Clogged exhaust gas recirculation cooler
  • Engine overheating

Diagnostic and repair procedures

A good starting point is always to check the Technical Service Bulletins (TSB) for your particular vehicle. Your problem may be a known issue with a known manufacturer-released fix and could save you time and money while troubleshooting.

Some type of diagnostic scanner, a digital volt/ohmmeter, a vehicle service manual (or equivalent), and an infrared thermometer with a laser pointer are all tools I would use to diagnose a P2457.

I could start by visually inspecting the wiring harnesses and connectors associated with the EGR temperature sensor and the exhaust gas temperature sensor. Closely inspect wire harnesses that are in the vicinity of hot exhaust pipes and manifolds. Test the battery under load, check the battery terminals, battery cables and generator output before proceeding.

I like to connect the scanner to the car and retrieve all stored codes and freeze frame data at this time. Make a note of the information because you may need it if it turns out to be a discontinuous code.

I monitored the data stream of the scanner to determine if the EGR was actually cooling. Narrow your data stream to include only the information you need for a faster, more accurate response. If the scanner shows actual temperature inputs are within specifications, suspect a defective PCM or PCM programming error.

If the readings from the exhaust gas recirculation temperature sensor are inaccurate or out of range, check the sensor following the manufacturer's recommendations. Replace the sensor if it does not meet manufacturer's specifications. If the sensor is in good condition, begin testing the EGR temperature sensor circuit. Disconnect all associated controllers before testing with DVOM. Repair or replace open or shorted circuits as necessary.

If the electrical system of the EGR temperature sensor is working properly, use an infrared thermometer to check the exhaust gas temperature at the EGR cooler inlet and at the EGR cooler outlet (with the engine running and at normal operating temperature). Compare the results obtained with the manufacturer's specifications and replace defective components if necessary.

Additional diagnostic notes:

  • Aftermarket mufflers and other exhaust system components can cause fluctuations in exhaust gas temperature, which could result in this code being stored.
  • Exhaust back pressure problems caused by an inadequate diesel particulate filter (DPF) are known to affect the storage conditions of P2457.
  • Diagnose and repair codes related to DPF before attempting to diagnose this code.
  • If the EGR system has been modified using an EGR lockout kit (currently offered by OEM and aftermarket), this type of code can be stored.

Related DTC discussions

  • 2014 VW Passat 2.0TDI P2457 – price: + XNUMX rub.Does anyone have any coolant flow diagram for VW Passat 2014 TDI 2.0. The mine has overheated the other day and check if the engine light with code P2457 (EGR cooling performance) comes on. Works fine in a barn at idle speed, the temperature rises to 190 and stays there. The other day I noticed ... 

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