P2490 code meaning
EGR Cooler Bypass Control Circuit Low (Bank 2)
Powertrain system Generic code P24xx codes Check engine light
What P2490 means
P2490 means the drive line of the bank 2 cooler bypass actuator sits too close to ground potential, typically a grounded wire between controller and actuator. It mirrors P245C on bank 1. No manufacturer documents P2490 publicly. GM's 2017 diesel tables give an idea of the bank 1 test: the vacuum-switched bypass is failed when the resistance to ground falls below 0.5 Ohm in 24 of 30 samples. Depending on the wiring, a grounded control line can keep the actuator permanently energised or permanently released, so bank 2 either always bypasses or always cools. Look for chafed insulation near the exhaust manifolds and turbocharger, harness clips lost after repairs and water in the connector. An open is P248E, a short toward the supply P2491.
P2490 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium, DIY possible
- Typical labor0.5 to 3 hours
- Clears after repairAfter a drive cycle
Symptoms of P2490
- Check engine light on
- Bypass on bank 2 stuck in one mode, possibly followed by cooler efficiency codes
Common causes of P2490
- Most likelyDrive wire rubbed through and touching engine ground
- PossibleWater or corrosion in the bank 2 actuator connector
- Less likelyInternal short in the actuator
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
EGR cooler bypass valve b2
What each part of P2490 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 4 | Area: auxiliary emission controls (catalytic converter, EGR, EVAP). |
| 90 | The exact fault in that area. |
What to do next
- Note P2490 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2490
What does P2490 mean?
P2490 means "EGR Cooler Bypass Control Circuit Low (Bank 2)". P2490 means the drive line of the bank 2 cooler bypass actuator sits too close to ground potential, typically a grounded wire between controller and actuator. It is a generic code, so it means the same on every make.
Is it safe to drive with P2490?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2490 fail an emissions test?
Yes, it can. P2490 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2490 to fix?
Difficulty: medium. A typical repair takes 0.5 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P2490 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.