P0403: How to Diagnose & Fix — Exhaust Gas Recirculation Circuit Malfunction
11 vehicles · 9 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 until coolant flow is restricted, causing the cooler to overheat and 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 issued TSBs for 2011-2014 trucks covering EGR cooler cleaning/replacement under extended warranty up to 120,000 miles. 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+). Check if truck qualifies for Ford extended service coverage with active DTC P0401 (Insufficient EGR Flow) or P2457 (EGR Cooler Performance). Some 2011-2014 trucks covered to 120,000 miles. 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 (1)
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)
Toyota Prius V · 2012–2017
The Prius V uses an EGR (Exhaust Gas Recirculation) cooler that produces condensation during short trips and cold weather driving. This condensation mixes with exhaust gases to form carbon deposits in the intake manifold and on the intake valves. Over time, the carbon buildup restricts airflow, causing rough idle and reduced fuel economy. The EGR valve itself can also become stuck from carbon accumulation. This is more prevalent in cold climate Prius V models driven primarily for short trips.
Common Symptoms
- Rough idle especially in cold weather
- Check engine light with EGR-related codes
- Reduced fuel economy (3-5 MPG drop)
- Hesitation during acceleration
- Engine stalling at idle
How to Fix
Clean the EGR valve and intake manifold ports using a carbon solvent (CRC GDI IVD Intake Valve & Turbo Cleaner). For severe buildup, the intake manifold must be removed for manual cleaning. Replace the EGR valve if it's stuck open or closed. Extended highway driving periodically helps burn off light deposits. Some owners install a catch can on the EGR line to trap condensation.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 04004-58137 EGR valve kit
replace a bulletin-confirmed sticking EGR valve as part of the complete Toyota repair procedure Fitment/availability: Toyota bulletin repair kit for the specified sticking-EGR-valve condition on covered early Prius/Prius v/Prius PHV appl…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- TipTake the Prius V on a 20+ minute highway drive weekly to bring the engine to full operating temperature — this helps burn off EGR condensation and deposits
- TipClean the EGR valve every 60,000 miles as preventive maintenance — a $150 cleaning prevents a $600 intake manifold removal job later
Peugeot 308 · 2007–2021
Citroen C4 · 2004–2021
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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 11 vehicle models from 9 manufacturers: Chrysler, Citroen, Ford, Land Rover, Mazda, Peugeot, Porsche, Toyota, Volkswagen.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.