P0403 on GMC
Exhaust Gas Recirculation Circuit Malfunction
P0403 on GMC vehicles indicates exhaust gas recirculation circuit malfunction. Au7o has documented this code across 5 GMC models — most commonly on Acadia, Canyon, Sierra 2500HD. 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 GMC range from $150 to $4,500, 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 GMC by Model
GMC Acadia(1 issue)
- 9T65 9-Speed Transmission Harsh Shifts and Hesitation2017-2025
The second-generation Acadia (2017+) uses the GM 9T65 9-speed automatic transmission which shares known issues with the Chevrolet Traverse and Blazer. Common complaints include harsh 1-2 upshifts, hesitation between 5-15 mph, lurching on light throttle in stop-and-go traffic, and the transmission hunting between gears on hills. GM has released multiple TCM calibration updates. The transmission is extremely sensitive to fluid condition — extended intervals with aging Dexron HP fluid contribute significantly to shift quality degradation.
GMC Canyon(1 issue)
- 8L45 8-Speed Transmission Torque Converter Shudder2015-2025
The 2015+ Canyon with the 3.6L V6 uses the GM 8L45 8-speed automatic (smaller sibling of the 8L90 in full-size trucks) which suffers the same torque converter lock-up clutch shudder at light throttle between 25-50 mph. The clutch friction material degrades and contaminates the fluid. GM issued TSB 18-NA-355 and Customer Satisfaction Program 18302 extending coverage to 6 years/100,000 miles. The fix and fluid are identical to the Sierra 1500 8L90 procedure — Mobil 1 Synthetic LV ATF HP (GM 19417577). This is the same issue affecting the Chevrolet Colorado V6.
GMC Sierra 2500HD(1 issue)
- Front Axle Disconnect Actuator and IWE Hub Failure (4WD Engagement Issues)2011-2023
Sierra 2500HD 4WD trucks use a front axle disconnect system with an electronic actuator and Integrated Wheel End (IWE) hubs. The actuator motor and position sensor commonly fail between 80,000-120,000 miles, causing the 4WD system to not engage, to partially engage (binding and vibration), or to throw a 4WD Service warning. Heavy-duty truck use — particularly towing and off-road — accelerates actuator wear. The IWE hubs (vacuum-operated on some variants, electric on others) also fail, causing a grinding or clicking noise from the front axle in 2WD mode when the hub disengages incompletely.
GMC Terrain(1 issue)
- 6T40/6T45 6-Speed Transmission Shudder and Harsh Shifts2010-2017
The 2010-2017 Terrain uses the GM 6T40 (2.4L) and 6T45 (V6) 6-speed automatic transmissions, both of which suffer from torque converter shudder, harsh shifts, and solenoid failures. The shudder occurs at light throttle between 30-50 mph when the torque converter clutch locks up. Solenoid pack wear causes P0756, P0751, and P0776 transmission fault codes. The transmission is sensitive to fluid condition — the 6T40/6T45 was originally filled with Dexron VI, but older Dexron VI degrades faster than newer formulations.
GMC Yukon(1 issue)
- 8L90 8-Speed Torque Converter Shudder2015-2020
The 8L90 8-speed automatic transmission in 2015-2020 Yukon and Yukon XL suffers from widespread torque converter lock-up clutch shudder at light throttle between 25-50 mph. The clutch friction material degrades and contaminates the transmission fluid, causing the shudder to worsen over time. GM extended warranty coverage to 6 years/100,000 miles under Customer Satisfaction Program 18302. The fluid fix (Mobil 1 Synthetic LV ATF HP, GM 19417577) resolves early-stage cases; advanced cases require torque converter replacement. This is the same issue affecting all K2XX platform full-size GM SUVs and trucks.
Looking for P0403 on a different make?
View P0403 across all makes →Frequently Asked Questions
What does P0403 mean on GMC?▼
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 GMC specifically, this code is documented across 5 models.
What causes P0403 on GMC vehicles?▼
Common causes on GMC: 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 GMC?▼
Repair costs on GMC range from $150 to $4,500, depending on the specific model and root cause.
Which GMC models have P0403 documented?▼
Au7o has documented P0403 on 5 GMC models: Acadia, Canyon, Sierra 2500HD, Terrain, Yukon.