Drivers first notice a lit check‑engine light that may be accompanied by a brief loss of engine power, especially under heavy load or when the turbo is active. The vehicle’s computer may also command a lean‑fuel condition, which can be observed as a sudden drop in throttle response or a “limp‑mode” behavior. In some cases the engine may run slightly richer as the ECM tries to compensate for the perceived temperature anomaly, leading to a modest increase in fuel consumption. These signs appear because the ECM is protecting the turbocharger and emissions system when the EGT sensor signal is out of its expected range.
Corrosion, chafing, or loose pins in the harness that runs from the sensor to the ECM can introduce resistance or intermittent breaks. The resulting voltage drop pushes the sensor reading outside the calibrated window, triggering P2488.
The ECM (or PCM) processes the EGT sensor voltage through an internal A/D converter. Software glitches, corrupted calibration data, or a failing internal circuit can cause the module to misinterpret a normal sensor voltage as out‑of‑range, prompting the fault.
Over time the thermistor element inside the EGT sensor can drift, producing a voltage that is consistently higher or lower than the reference range. While the sensor itself is a hardware component, the ECM’s ability to compensate is limited, so the fault persists until the sensor or its signal path is corrected.
Performance tunes that alter turbo boost or fuel maps may push exhaust temperatures beyond the original design envelope. If the ECM’s adaptive strategy cannot accommodate the new range, it will log P2488 to protect the engine.
Connect a professional OBD‑II scanner, record the exact P2488 description, and note any related codes (e.g., other EGT sensor codes or turbo‑charger codes). Clear the codes to see if they return after a drive cycle.
With the engine at idle and then under load, monitor the Bank 2 Sensor 5 voltage (typically 0.5‑4.5 V). Compare the reading to the manufacturer’s specifications. A steady voltage within range indicates a healthy sensor; a fluctuating or out‑of‑range value points to wiring or sensor issues.
Locate the sensor harness on Bank 2 (the side of the engine opposite the driver). Inspect for cracked insulation, corrosion, or loose connectors. Use a multimeter to verify continuity and resistance (should be less than 5 Ω). Repair any damaged sections with heat‑shrink tubing or replace the connector if needed.
Perform a module communication verification using the scanner’s “ECU/PCM” test. Check for error messages such as “ECU communication failure” or “Calibration data corrupted.” If the ECM fails the test, re‑flash the latest calibration file from the manufacturer’s service portal.
Disconnect the sensor plug and measure the resistance of the sensor element (typically 1 kΩ at 25 °C). Compare to spec; a significantly higher resistance suggests sensor degradation. If the sensor checks out, the fault likely resides in the ECM.
When the sensor and wiring are sound, update the ECM’s software to the latest version. This step often resolves hidden bugs that cause false‑range detections. Re‑calibrate the EGT sensor following the manufacturer’s procedure (usually a “cold start” followed by a “warm‑up” cycle).
After repairs, clear all codes and conduct a road test covering idle, acceleration, and high‑load conditions. Confirm that the MIL remains off and that power delivery is normal. Re‑scan to ensure no new codes appear.
Cost Estimates
Service Recommendation: Most issues related to this fault are diagnosed and corrected through inspection, wiring repair, and calibration rather than module replacement. For modules not typically replaced through aftermarket suppliers, diagnosis and repair should be performed by a certified automotive technician with access to factory service information and tooling.