Emission controls · Powertrain · generic (SAE-defined)
P0403: Exhaust Gas Recirculation "A" Control Circuit
P0403 means the engine computer has found an electrical problem in the circuit that controls the exhaust gas recirculation (EGR) valve or its control solenoid.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0403 sets
The powertrain control module (PCM) monitors the voltage on the EGR solenoid or electronic EGR valve driver circuit. When the circuit state does not match the command, such as an open, a short to ground, or a short to voltage, the PCM sets P0403. Circuit monitoring limits are manufacturer-specific.
Common causes of P0403
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Failed EGR valve solenoid or electronic EGR valve motor
- Damaged, corroded, or loose connector at the EGR valve or solenoid
- Open or shorted wiring between the PCM and the EGR component
- Blown fuse or loss of power feed to the EGR circuit
- Rarely, a failed driver inside the PCM
P0403 symptoms
- Check engine light on
- Rough idle or stalling if the valve is held open
- Pinging under load if the valve cannot open
- Sometimes no noticeable symptoms
How P0403 is diagnosed
- Scan for codes and freeze frame data; note any other circuit or voltage codes
- Inspect the EGR connector and harness for damage, corrosion, or heat chafing near the exhaust
- Check the relevant fuse and confirm power at the EGR component with the key on
- Measure the solenoid or valve coil resistance and compare to specification
- Check the control wire for continuity and shorts back to the PCM
- Use a bidirectional scan tool to command the valve and verify it responds
Typical fixes for P0403
- Replace the EGR solenoid or electronic EGR valve
- Repair the wiring harness or connector
- Replace a blown fuse after finding the cause
- Replace or reprogram the PCM only after all wiring tests pass
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Definitions can vary by manufacturer; check factory service information. Older SAE wording for this code is "Exhaust Gas Recirculation Control Circuit Malfunction."
Related codes & warning lights
P0403 FAQ
What does code P0403 mean?
P0403 means the engine computer has found an electrical problem in the circuit that controls the exhaust gas recirculation (EGR) valve or its control solenoid. The standard definition is "Exhaust Gas Recirculation "A" Control Circuit."
Can I drive with a P0403 code?
Usually yes for a short time. Depending on whether the valve is stuck open or closed, the engine may idle roughly or ping under load, so repair the circuit soon.
Is P0403 a mechanical or electrical problem?
It is an electrical circuit code. The valve may also be mechanically fine, so testing the wiring and the coil comes before replacing parts.
Can a blown fuse cause P0403?
Yes. If the EGR solenoid shares a fused power supply that has failed, the PCM will see an open circuit and set P0403.
Keep researching
More emission controls codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.