P0403: How to Diagnose & Fix — Exhaust Gas Recirculation Circuit Malfunction
9 vehicles · 7 makes · $60-$3,500 repair
How to diagnose and fix P0403: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Ford F-250 Super Duty · 2011–2019
The EGR (Exhaust Gas Recirculation) cooler on 2011-2019 6.7L Power Stroke diesel engines is prone to clogging with soot and eventually failing, particularly on trucks used for highway driving, light loads, or trucks that idle extensively. The EGR cooler recirculates cooled exhaust gas back into the intake to reduce NOx emissions. Over time, soot accumulates in the cooler's internal passages and restricts exhaust gas flow through the cooler core, and a cooler that overheats can fail. When it fails, exhaust gases enter the coolant system, causing overheating and "puking" coolant from the degas bottle. The 2011-2014 models are particularly susceptible due to narrow internal coolant passages. Ford TSB 13-6-5 (superseding 12-6-14) covers 2011-2012 6.7L trucks with DTC P0401 and P2457, calling for EGR cooler core replacement under normal New Vehicle Limited Warranty coverage. The EGR cooler for 2011-2016 is OEM part BC3Z-9V425-A; 2017+ is HC3Z-9V425.
Common Symptoms
- Coolant loss with no visible external leak
- Coolant reservoir overflows or "pukes" coolant
- White smoke from exhaust (coolant in combustion)
- Engine overheating warning
- DTC codes P0401 (Insufficient EGR Flow) or P2457 (EGR Cooler Performance)
- Bubbling or foaming in coolant degas bottle
- Loss of power under load (especially towing)
- White deposits around degas bottle cap
How to Fix
Replace EGR cooler (BC3Z-9V425-A for 2011-2016; HC3Z-9V425 for 2017+). For 2011-2012 trucks with DTC P0401 (Insufficient EGR Flow) and P2457 (EGR Cooler Performance), Ford TSB 13-6-5 applies; coverage follows the truck's normal warranty, so have a Ford dealer check the VIN. Preventive: use a fuel additive (Diesel Kleen, Hot Shots Secret EDT) to reduce soot. Perform regular EGR cleaning at 60,000-mile intervals. Upgrade kits from Sinister Diesel and Dorman (904-405 kit) include both EGR cooler and gaskets.
Sources for this issue (2)
Chrysler Crossfire · 2004–2008
The Crossfire (built on Mercedes SLK R170 platform, sharing 80% of components) commonly experiences EGR solenoid failures and premature catalytic converter failure. The EGR solenoid is the most common cause of check engine lights. Catalytic converter rattles and fails, especially noticeable when accelerating from cold.
Common Symptoms
- Check engine light (EGR codes)
- Rattling noise from underneath when accelerating from cold
- Failed emissions inspection
- Rough idle
- Reduced fuel economy
How to Fix
Replace EGR valve (Mercedes part A6121400060, fits Crossfire directly). Replace catalytic converter if rattling. Many Mercedes SLK R170 parts are direct replacements at lower cost. Use Mercedes dealer or independent Mercedes shop for best results.
Sources for this issue (1)
Peugeot 308 · 2007–2021
The exhaust gas recirculation valve on diesel 308 models becomes clogged with carbon deposits, causing rough idle and poor performance. The electrically actuated valve sticks in the open or closed position.
Common Symptoms
- Rough idle
- Black exhaust smoke
- Loss of power
- Check engine light
How to Fix
Clean or replace the EGR valve. Install an EGR cooler bypass blanking kit if permitted in your region. Update the ECU software to revised EGR control maps.
Sources for this issue (1)
Volkswagen Jetta · 2009–2014
Porsche Macan · 2014–2018
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P0403 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0403 mean?
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.
What are the most common causes of P0403?
The most common causes of P0403 are: 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. The specific cause varies by vehicle.
How much does it cost to fix P0403?
Repair costs for P0403 range from $60 to $3,500, depending on the vehicle and root cause.
Which vehicles are affected by P0403?
Au7o has documented P0403 across 9 vehicle models from 7 manufacturers: Chrysler, Ford, Land Rover, Mazda, Peugeot, Porsche, Volkswagen.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.