P0403 on Cadillac
Exhaust Gas Recirculation Circuit Malfunction
P0403 on Cadillac vehicles indicates exhaust gas recirculation circuit malfunction. Au7o has documented this code across 3 Cadillac models — most commonly on CTS, CTS-V, Escalade. This emissions code indicates a malfunction in the exhaust gas recirculation (EGR) control circuit. The EGR system routes a small amount of exhaust back into the intake to lower combustion temperatures and reduce nitrogen-oxide emissions, and the computer commands the EGR valve open and closed through this circuit. The code sets when the electrical control signal to the EGR valve or its solenoid is out of the expected range — for example, an open, short, or a commanded change that doesn't produce the right feedback. It generally points to an electrical or wiring problem in the EGR control circuit, or the EGR valve/solenoid itself, rather than carbon clogging alone. Typical repair costs on Cadillac range from $800 to $3,500, depending on the specific model and root cause.
Common Causes of P0403
- •Faulty EGR valve or EGR solenoid
- •Damaged wiring or connector in the EGR control circuit
- •Open or short in the EGR control wiring
- •Corroded or loose EGR connector
- •Blown fuse or lost power supply to the EGR circuit
- •Carbon buildup binding the EGR valve
- •Faulty engine control module or driver circuit
P0403 on Cadillac by Model
Cadillac CTS(1 issue)
- Electric Power Steering Rack Failure2008-2013
The 2nd generation CTS (2008-2013) uses an electric power steering rack that can fail, causing heavy or intermittent steering assist. The electric motor integrated into the steering rack wears out, or the steering control module loses communication. Symptoms include sudden loss of power steering assist (steering becomes very heavy), intermittent assist that cuts in and out, and steering warning lights. The entire rack assembly must be replaced as the motor is not serviceable separately.
Cadillac CTS-V(1 issue)
- Magnetic Ride Control Shock Failure2009-2019
The CTS-V (2nd and 3rd gen) comes standard with Magnetic Ride Control (MRC) shocks that use magnetorheological fluid to adjust damping. These expensive shocks have a limited lifespan, typically 60,000-100,000 miles, after which the MR fluid degrades and the shocks either become too stiff, too soft, or leak. Replacement with OEM MRC shocks is very expensive ($500-800 per shock). Many owners switch to traditional high-performance shocks to avoid the recurring cost.
Cadillac Escalade(1 issue)
- Air Suspension / Magnetic Ride Control Compressor Failure2007-2020
The Cadillac Escalade with Autoride (air suspension) or Magnetic Ride Control uses an air compressor and electronic shocks that commonly fail between 80,000-120,000 miles. The air compressor burns out from continuous cycling caused by slow air leaks in the air springs (bags). Failed air springs cause the vehicle to sag at one or more corners, and the compressor overworks trying to compensate. The Magnetic Ride Control shocks contain magnetorheological fluid that degrades over time, causing a harsh or bouncy ride. Common on 2007-2014 (3rd gen) and 2015-2020 (4th gen) Escalades equipped with these options.
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View P0403 across all makes →Frequently Asked Questions
What does P0403 mean on Cadillac?▼
P0403 stands for "Exhaust Gas Recirculation Circuit Malfunction." This emissions code indicates a malfunction in the exhaust gas recirculation (EGR) control circuit. The EGR system routes a small amount of exhaust back into the intake to lower combustion temperatures and reduce nitrogen-oxide emissions, and the computer commands the EGR valve open and closed through this circuit. The code sets when the electrical control signal to the EGR valve or its solenoid is out of the expected range — for example, an open, short, or a commanded change that doesn't produce the right feedback. It generally points to an electrical or wiring problem in the EGR control circuit, or the EGR valve/solenoid itself, rather than carbon clogging alone. On Cadillac specifically, this code is documented across 3 models.
What causes P0403 on Cadillac vehicles?▼
Common causes on Cadillac: Faulty EGR valve or EGR solenoid, Damaged wiring or connector in the EGR control circuit, Open or short in the EGR control wiring, Corroded or loose EGR connector, Blown fuse or lost power supply to the EGR circuit. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0403 on a Cadillac?▼
Repair costs on Cadillac range from $800 to $3,500, depending on the specific model and root cause.
Which Cadillac models have P0403 documented?▼
Au7o has documented P0403 on 3 Cadillac models: CTS, CTS-V, Escalade.