OBD-II code P2488 indicates that the powertrain control module (PCM) has detected a range or performance problem in the exhaust gas temperature (EGT) sensor circuit on Bank 2, Sensor 5. The sensor's signal is reading outside of the expected parameters for current operating conditions, or the signal is stuck or implausible relative to other sensors. EGT sensors are commonly used on diesel applications to monitor temperatures around the diesel particulate filter (DPF), selective catalytic reduction (SCR) catalyst, or NOx traps, and to help control regeneration events.
EGT sensors are exposed to extreme heat cycles and thermal shock, making them the most common point of failure. The internal thermocouple or thermistor can drift out of calibration, open, or short internally, producing a stuck or out-of-range signal.
The wiring leading to the downstream EGT sensor passes through the hot underbody and is exposed to heat, vibration, road debris, and exhaust-soak conditions. Melted, chafed, or broken wires are a frequent cause of range/performance faults.
Moisture, road salt, and high exhaust heat can corrode the sensor's electrical connector or its pins, causing high resistance, intermittent contact, or an open circuit that confuses the PCM.
An open in the signal wire, a short to ground, or a short to voltage anywhere between the sensor and the PCM can place the reading outside the expected range. Connector terminal tension loss is also common.
A heavily loaded DPF, a restricted or failing SCR catalyst, or excessive soot loading can cause the downstream temperature to be abnormal. The sensor is then reporting correctly, but its reading is flagged because it does not match expected values for current engine conditions.
A failed PCM or its input circuitry is an uncommon cause of P2488 and should be considered only after the sensor, wiring, connector, and exhaust condition have all been ruled out. Replacing the PCM on a guess is one of the most common and most expensive misdiagnoses for this code.
No. The exhaust gas temperature sensor itself and the wiring/connector to it fail far more often than the powertrain control module. Replacing or reprogramming the PCM is one of the most common and most expensive mistakes made for this code, and the sensor and its circuit should be fully checked first.
On most diesel applications, short-term driving is usually possible, but the PCM may disable DPF regeneration or derate engine power to protect the exhaust aftertreatment system. Driving for an extended period with the code active can lead to a clogged DPF, reduced fuel economy, or a vehicle that enters limp mode.
Bank 2 is the engine bank that does not contain cylinder 1. Sensor 5 generally refers to a position farther downstream in the exhaust, often after the diesel particulate filter or SCR catalyst. The exact physical location varies by engine and vehicle and should be confirmed with a service manual.
Not usually. P2488 is a sensor circuit code, not a direct DPF performance code. A failing or loaded DPF can contribute to an abnormal downstream temperature reading, but the sensor, its wiring, and its connector are the more common causes and should be verified before any aftertreatment component is replaced.