OBD-II code · Powertrain (generic)
P0490 EGR A Control Circuit High
EGR A drive line stuck high — short to B+. EGR mixes inert exhaust into intake to lower combustion peak temperature — too little raises NOx, too much causes misfires and rough running.
Is it safe to drive with P0490?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyShort to B+
- Less likelyConnector pins corroded - high contact resistance
- Less likelySupply wire pinched against B+ source
Symptoms
- Check engine light on
- Pinging or knocking under load
- Power loss and hesitation
- Possible rough idle
- Failed emissions inspection (NOx)
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–2.5 h
- Emissions test
- Likely to fail
- Parts involved
- Egr Valve
Related codes
- P045DEGR B Control Circuit High
- P0489EGR A Control Circuit Low
- P23E4EGR C Control Circuit High
- P048DExhaust Pressure Control Valve A Position Sensor/Switch Circuit Low
- P048EExhaust Pressure Control Valve A Position Sensor/Switch Circuit High
- P048FExhaust Pressure Control Valve A Position Sensor/Switch Circuit Intermittent/Erratic
- P0491Secondary Air Injection System Insufficient Flow (Bank 1)
- P0492Secondary Air Injection System Insufficient Flow (Bank 2)
- P0493Fan Overspeed
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.