P2494EGR Cooler Bypass Position Sensor Circuit Low (Bank 1)
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2494 is set when the raw voltage of the bank 1 bypass position sensor drops toward zero. GM documents it for the Duramax diesel: in the 2017 tables the signal must be below 1 % of the 5 V reference in 200 of 250 samples, checked every 6.25 ms once cranking is over and the powertrain relay supplies more than 11 V. The 2018 tables keep the test and the Type B rating, so the lamp comes on after two trips. GM groups P2494 with P2495 and P24C4 in one sensor fault bundle, which makes the bypass control fall back to a default. A signal near zero points to a short to ground, a missing 5 V supply or a broken signal wire pulled down inside the controller. High voltage is P2495; on bank 2 the low case is P2499.
- What you may notice
- Check engine light after two trips
- Bypass control falls back to a default position
- Likely causes
- LikelySignal wire shorted to ground
- PossibleOpen 5 V reference wire to the sensor
- PossibleInternal sensor fault in the bypass valve
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €30 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.