P0403: Exhaust Gas Recirculation "A" Control Circuit
The engine computer has found an electrical problem in the circuit that controls the EGR valve or its vacuum solenoid.
What P0403 means
Many engines control EGR with a vacuum solenoid, while newer ones use an electric EGR valve with its own motor. Either way, the engine computer switches the circuit and watches the voltage. RepairPal explains that P0403 means the computer is not seeing the proper EGR vacuum solenoid voltage when it allows or denies vacuum to the valve. In other words, this is an electrical code. The most common causes are a failed solenoid or electric valve, an open or shorted wire, a bad connector and a blown fuse. If the EGR cannot be controlled, it may stay closed, which can cause pinging under load, or stay open, which can cause a rough idle. Shops check resistance of the solenoid coil, verify power and ground at the connector, and command the solenoid with a scan tool while watching for a click and vacuum change. On electric valves they also check the position sensor feedback. Once the circuit is repaired, the code usually clears right away.
Common symptoms
- Check engine light on
- Pinging on acceleration or under load
- Failed emissions test
- Rough idle if the valve is stuck open
- Often no other symptoms
Most common causes
- Failed EGR vacuum solenoid or electric EGR valve
- Open or shorted wiring in the control circuit
- Corroded or loose connector
- Blown fuse for the EGR circuit
- Engine computer driver fault (rare)
What to check yourself first
Find the EGR valve or its vacuum solenoid and check the connector for corrosion or a broken latch. Check the fuse for the EGR circuit. Look for wires melted against exhaust parts.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Replace EGR vacuum control solenoid | $129-$151 | RepairPal lists a defective EGR vacuum solenoid as the top cause. |
| Replace EGR valve | $489-$632 | On electric EGR valves, the valve and its motor are one part. |
| Electrical diagnosis to find a wiring or connector fault | $122-$179 | For wiring or connector faults. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0404 Exhaust Gas Recirculation "A" Control Circuit Range/Performance
- P0400 Exhaust Gas Recirculation "A" Flow
- P0401 Exhaust Gas Recirculation "A" Flow Insufficient Detected
- P0402 Exhaust Gas Recirculation "A" Flow Excessive Detected
- P0325 Knock Sensor 1 Circuit (Bank 1 or Single Sensor)