Technical Description of OBD-II Trouble Code
Performance Issue in the Exhaust Gas Recirculation Cooling System
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to all vehicles manufactured from 1996 onwards (Ford, Dodge, GMC, Chevrolet, Mercedes, VW, etc.). While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
If your OBD-II equipped vehicle displays a P2457 code, it indicates that the powertrain control module (PCM) has detected a potential malfunction in the exhaust gas recirculation (EGR) cooling system. This malfunction could be either mechanical or electrical in nature.
The EGR system is responsible for redirecting a portion of the exhaust gases back into the intake manifold so that they can be burned again. This process is necessary to reduce the release of nitrogen oxide (NOx) particles into the atmosphere. NOx is a contributing factor to the depletion of ozone in exhaust emissions.
EGR cooling systems are typically found in diesel engine equipped vehicles. Engine coolant is used to lower the temperature of the engine exhaust gases before they enter the EGR valve. The PCM receives input signals from the EGR temperature sensor and an auxiliary exhaust temperature sensor to determine if the EGR cooling system is functioning efficiently.
The EGR cooler is usually designed like a small radiator or heater core, with fins on the outside, a coolant inlet and outlet, and one or more exhaust pipes or tubes running through the center. Air passes over the fins to cool both the coolant flowing around the outer diameter of the cooler and the exhaust flowing through the center.
The auxiliary exhaust temperature sensor is typically located in the down pipe, while the EGR temperature sensor is positioned near the EGR valve. If the input signal from the EGR temperature sensor does not meet the programmed specifications, or if it is not significantly lower than that of the auxiliary exhaust temperature sensor, a P2457 code will be stored and the malfunction indicator lamp may illuminate.
Symptoms & Severity
Since the P2457 code is related to the exhaust emissions system, it is not considered an urgent code. Symptoms that may be associated with a P2457 code include:
Causes
Possible causes for the occurrence of this code are:
Diagnostic and Repair Procedures
It is always advisable to start by checking for any technical service bulletins (TSB) specific to your vehicle. There may be a known issue with a known solution provided by the manufacturer, which can save time and money during the diagnosis process.
To diagnose a P2457 code, you will need some tools such as a diagnostic scanner, a digital volt/ohmmeter, a vehicle service manual (or equivalent), and an infrared thermometer with a laser pointer.
A visual inspection of the wiring harnesses and connectors associated with the EGR temperature sensor and the exhaust temperature sensor is a good starting point. Pay close attention to harnesses that are in close proximity to hot exhaust pipes and manifolds. Before proceeding, load test the battery, check the battery terminal ends, battery cables, and alternator output.
Connect the scanner to the vehicle and retrieve all stored codes and freeze frame data. Record this information as it may be needed if the code is intermittent.
Observe the data stream on the scanner to determine if the EGR cooling is actually taking place. Narrow down the data stream to include only relevant information for a quicker and more accurate response. If the scanner indicates that the actual temperature inputs are within specifications, suspect a defective PCM or a PCM programming error.
If the data from the EGR temperature sensor is erratic or does not meet the desired parameters, test the sensor according to the manufacturer’s recommendations. Replace the sensor if it fails to meet the manufacturer’s specifications. If the sensor is in good condition, proceed to test the EGR temperature sensor circuitry. Disconnect all related controllers before testing with the DVOM. Repair or replace any open or shorted circuits as necessary.
If the electrical system of the EGR temperature sensor appears to be functioning normally, use the infrared thermometer to measure the exhaust gas temperature at the EGR cooler inlet and outlet while the engine is running at normal operating temperature. Compare your findings with the manufacturer’s specifications and replace any faulty components as needed.
Additional diagnostic notes:
