Code
P2490
Generic
P — Powertrain
EGR Cooler Bypass Control Circuit Low Bank 2
Views:
UK: 18
EN: 36
RU: 23
AI status
Completed
Completed
100%
Causes
- Short to ground in the EGR cooler bypass control wiring (bank 2)
- Corroded, disconnected or damaged connector at the bypass valve/solenoid
- Failed EGR cooler bypass actuator/solenoid (stuck open/shorted)
- Open or high-resistance circuit between PCM and valve
- PCM or driver transistor fault
- Aftermarket modifications or recent repairs that disturbed wiring
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine performance or drivability issues
- Rough idle or stalling in some conditions
- Decreased fuel economy
- Increased NOx/exhaust emissions or failed emissions test
What to check
- Retrieve freeze frame and live data with a scan tool; note EGR bypass command and feedback
- Verify battery voltage and ground integrity before testing circuits
- Visually inspect wiring harness and connector for damage, contamination, or pin corrosion
- Back-probe connector and measure voltage at rest and while commanding the bypass
- Check resistance of bypass actuator/solenoid against specification
- Wiggle-test harness while monitoring live data for intermittent faults
Signal parameters
- Expected control voltage: approx. 0–12 V depending on system (verify manufacturer spec)
- Circuit low condition: measured voltage near 0 V when circuit should be higher (indicates short to ground or open reference)
- Coil/solenoid resistance: typically a few ohms to several tens of ohms (check service spec)
- PCM command: may be PWM duty cycle or switched ground; monitor commanded state vs actual voltage
- Current draw: abnormal low or high current indicates open circuit or shorted coil respectively
Diagnostic algorithm
- Read and record all stored codes and freeze frame data. Confirm P2490 is present and note any related EGR or electrical codes.
- Clear codes, perform a key-on/start cycle and attempt to reproduce. Monitor live data for EGR cooler bypass command and any feedback signal.
- Visually inspect harness, connector and valve on bank 2 for damage, corrosion, crushed wires or signs of overheating.
- With ignition off, disconnect the bypass valve connector. Measure resistance across the valve/solenoid terminals and compare to spec. If open or shorted, replace valve.
- With connector connected, back-probe the control pin. With key on, engine off, verify reference voltage or ground reference as specified. Command the valve on using a scan tool and confirm voltage/duty cycle changes accordingly.
- If control voltage stays near 0 V when commanded ON, isolate wiring: disconnect at PCM and measure for short to ground toward the harness. Check continuity to ground.
Likely causes
- Wiring chafed and shorted to ground near engine or harness
- Connector pins corroded or pushed out at the bypass valve
- Bypass valve internal coil failed (low resistance/short)
- Ground strap or ground point for bank 2 circuit is poor
- PCM output driver on bank 2 has failed
Fault status
Status
EGR cooler bypass control circuit voltage low — bank 2 (circuit below expected range).
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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