Emissions control: EGR, DPF, catalytic converter and AdBlueGeneric OBD-II codeUrgency: Garage soon
Code P0404: EGR circuit range or performance
P0404 means: exhaust gas recirculation (EGR): circuit range/performance.[1][2][3] P0404 indicates that, with the engine running, the position of the EGR valve or the flow of gases does not match what the control unit expects. According to Autodoc, what falls outside the expected parameters is the position of the valve or that of its position sensor.[1][2][3]
What code P0404 means
P0404 indicates that, with the engine running, the position of the EGR valve or the flow of gases does not match what the control unit expects. According to Autodoc, what falls outside the expected parameters is the position of the valve or that of its position sensor.[1][2][3]
It is a plausibility fault: TAT explains that the measured value is within the electrical range, but is not consistent with the expected behaviour. Pierburg distinguishes it from P0403 (control loop fault, with incorrect or inconsistent signals): in P0404 what falls outside the expected range is the recirculation. The causes range from soot that prevents the valve from moving to sensors, connectors or leaks.[1][2][4]
It is a generic OBD-II code: the 0 after the P indicates that it is defined by the SAE standard, so it means the same thing on any make.[5]
Original definition (SAE J2012): Exhaust Gas Recirculation Circuit Range/Performance[1][2][3]
Causes of P0404
From most to least likely, according to the sources.
- 1Soot and carbon deposits in the EGR valve (seat or stem), in the passages or in the manifold recirculation pipe.[1][3][6]
- 2Faulty or stuck EGR valve, often stuck closed.[1][3][6]
- 3Damaged EGR position sensor.[1][2][3]
- 4Loose, corroded or heat-damaged connectors and wiring on the sensor or the valve, or a short circuit in the circuit.[1][3][6]
- 5Faulty vacuum hoses, or no vacuum or electrical signal reaching the valve.[1][3]
- 6Leak in the intake or in the EGR pipes, or faulty air mass meter or MAP sensor.[4][6]
- 7Dirty or damaged EGR gaskets, or faulty EGR pressure sensor.[1][4]
- 8Control unit fault, in its software or in the unit itself.[1][6]
Symptoms
- Engine warning light on.[6]Engine warning light: faults that cause it
- Uneven idle.[1][6]Vibrations: faults that cause it
- Loss of power, especially at low revs.[1]Less power: faults that cause it
- Difficulty starting from cold.[1]Hard to start: faults that cause it
- Higher fuel consumption.[1][6]Uses more fuel: faults that cause it
- Dark smoke from the exhaust.[1]Black smoke: faults that cause it
- Metallic knocking noises from the engine bay.[1]
- Increased polluting emissions.[1][6]
How to diagnose P0404
In order: from the most likely and cheapest to check to the most expensive.
- 1Read the codes and the freeze-frame data with diagnostic equipment, clear the code and do a road test to see whether it comes back.[3][6]
- 2Check the electrical connections of the sensor and the valve (frayed wires, corrosion) and the vacuum hoses.[1][6]
- 3Remove the valve and look for carbon deposits on the seat and in the intake manifold passages; clean or replace the valve together with its gaskets.[1][3][6]
- 4Check the EGR position sensor; if you replace it, carry out the basic setting afterwards.[1]
- 5Look at the air mass meter and MAP sensor values and look for leaks in the intake and in the EGR pipes.[4][6]
- 6Compare the EGR signals with the reference values and check lines, connectors and components: wear or dirt on the sensors can falsify the readings.[4]
- 7If everything is correct, check for software errors in the control unit and reprogram if appropriate. Replace the valve or the sensor only when the tests indicate it.[1][6]
Can I keep driving with P0404?
Garage soon
Autodoc allows short journeys, but asks you to go to the garage as soon as possible, because the fault can increase consumption and damage the engine. Mechanicbase rates it as medium severity and warns that continuing to drive with the fault can end in bigger engine problems.[1][6]
Documented faults related to P0404
Known faults of specific engines and cars, with their repair cost, the affected years and their sources.
EGR valve: the most serious faults by engine and car
- Critical severityFrequency: Very frequentBMW B47EGR cooler leaks with risk of engine fireYes: the EGR valve cooler can suffer internal coolant leaks which, mixed with soot and oil, can reach combustion temperatures; BMW has launched several technical campaigns since 2018 to inspect and replace it because of the risk of engine fire.Repair (garage): €500–€1,500
- Critical severityFrequency: Very frequentBMW N57EGR cooler leaks with risk of engine fireYes: like the N47 and B47, the N57 is covered by BMW's service campaign for EGR cooler leaks, which can mix coolant with soot and oil to combustion temperatures. BMW checks free of charge the 6-cylinder engines built between July 2012 and June 2015 because of the fire risk.
- High severityFrequency: Very frequentOM651EGR and particulate filter clogging, and emissions software updatesThe particulate filter and EGR clog up with short journeys, as on any diesel with these systems. In addition, Germany's KBA required software updates on several models with this engine between 2018 and 2021 because of a function that reduced EGR outside a temperature range.Repair (garage): €800–€2,500
- Medium severityFrequency: Very frequentOM642Emissions defeat device (AdBlue/EGR) and software update campaignGermany's KBA found indications of emissions manipulation in cars with the OM642 engine (alongside the OM651): AdBlue dosing and the EGR changed between the test bench and the road. Mercedes-Benz denied it, but in 2018 it recalled hundreds of thousands of diesels in Europe.
Carbon build-up in the intake: the most serious faults by engine and car
- Medium severityFrequency: Very frequent2.0 TSI / TFSICarbon build-up on the intake valvesBecause the fuel is injected directly into the cylinder, no petrol washes over the intake valves, so oil residue and soot build up and, over the years, restrict airflow and affect engine response.
- Medium severityFrequency: Common1.6 HDiLeaks at the injector washers and carbon build-up in the cylinder headIt is common for the copper washers of the 1.6 HDi injectors to stop sealing: the engine blows gases, carbon forms around the injector and soot gets into the oil. It is cheap to repair, but if left it contaminates the oil and is one of the causes of turbo failure.Repair (garage): €110–€310
- Medium severityFrequency: Common1.0 T-GDICarbon build-up on the intake valves and coking of the injectorsThe direct injection on the 1.0 T-GDI does not wash the intake valves with fuel, so over the kilometres carbon builds up on them and on the injectors. It causes loss of power, jerking and higher fuel consumption; it is fixed by cleaning the manifold and valves, without damaging the engine.
- Medium severityFrequency: Common1.6 GDI / T-GDICarbon build-up on the intake valvesBeing pure direct injection, with no port injectors to wash the valves, the 1.6 GDI and T-GDI build up intake carbon with mileage: unstable idle, jerking or loss of power. A design trait of all direct injection, not a manufacturing fault.
Engine sensors: the most serious faults by engine and car
- High severityFrequency: Occasional2.0 DTI and 2.2 DTIVP44 injection pump and air mass meter failureGerman Wikipedia documents recurring failures of the Bosch VP44 injection pump and the air mass meter in the early years of this engine. An owner testimony for this engine describes the pump being replaced at 192,500 km, at a cost the owner calls «prohibitive».
- Medium severityFrequency: Common2.0 TDIClogged particulate filter or faulty pressure sensorThe 2.0 TDI's particulate filter clogs if the car mostly makes short journeys, because it never gets to regenerate; sometimes the fault is just the differential pressure sensor. Cleaning it costs around €200 and replacing it, €800 to €3,000.Repair (garage): €800–€3,000
- Medium severityFrequency: Common1.4 and 1.6 8vCrankshaft position sensor failure (TDC sensor)The crankshaft position sensor (capteur PMH, or TDC sensor) appears repeatedly in the reliability sources for the Clio II, the Kangoo I and the Dacia Logan I with this engine, with hard cold starting or stalling as the main symptoms. It is a cheap part, but the failure can leave you stranded.
- Medium severityFrequency: Common1.4 and 1.6 16vCrankshaft position sensor failureThe crankshaft position sensor (capteur PMH) appears repeatedly in the reliability sources for almost every generation with this engine, with hard cold starting, stalling or the car cutting out unexpectedly. It is a cheap part, but the failure can leave you stranded.
Frequently asked questions
What does "range/performance" mean and how does it differ from P0403?
"Range/performance" means that the EGR signal is within what the control unit can read, but does not agree with what it should be at that moment: TAT calls it a plausibility fault. Pierburg distinguishes it from P0403, which is a control loop fault with incorrect or inconsistent signals, because in P0404 what falls outside the expected range is the recirculation.[2][4]
Is cleaning the EGR valve enough to clear P0404?
Cleaning is often the first step, because soot appears among the first causes and the sources ask for the valve seat and the manifold passages to be checked. But if the origin is the position sensor, a connection or a leak, cleaning does not solve it; that is why it is best to check the sensor, wiring and intake first.[1][3][6]
Can I drive with code P0404?
For short journeys and with the idea of going to the garage as soon as possible. Autodoc warns that the fault can increase consumption and damage the engine, and Mechanicbase rates it as medium severity and warns that continuing to drive can lead to bigger problems.[1][6]
Can an intake leak or the air mass meter cause a P0404?
Yes. Mechanicbase includes an intake leak and a faulty air mass meter or MAP sensor among the causes, and Pierburg cites wear or dirt on the air mass meter among the possible origins of inconsistent EGR signals. That is why it is best to look at their values before replacing the valve.[4][6]
Does P0404 mean the same on all makes?
Yes. It is a generic OBD-II code: those starting with P0 are defined by the SAE standard and have the same definition across all manufacturers. What varies from one engine to another is the type of EGR valve and the most likely cause.[4][5]
Will I pass the MOT with code P0404?
If the code has switched on the engine warning light, no: with that light on, the inspection records a serious defect, and on Euro 5 and Euro 6 cars the ITV (Spain's roadworthiness inspection, similar to the MOT) also reads the OBD diagnostic system. Repair the fault before you go; clearing the code just before the inspection does not help either, because it counts as a serious defect.[7]
Not sure what is wrong with your car? Describe what you notice in the symptom diagnosis or see all fault codes.
Sources
Every fact on this page links to its source. If you find an error, let us know.
- Código OBD2 P0404: causas, síntomas y cómo corregirloAutodoc Club · Technical documentation · consulted 2 October 2026 · in Spanish
- P0404: Exhaust Gas Recirculation Circuit Range/PerformanceThe Automotive Technician (TaT) · Technical documentation · consulted 2 October 2026
- P0404 code for EGR: What it means and how to fix itRick's Free Auto Repair Advice · Other source · published 6 August 2009 · consulted 2 October 2026
- OBD-SystemMS Motorservice (Pierburg) · Manufacturer · consulted 2 October 2026
- On-board diagnosticsWikipedia · Other source · consulted 2 October 2026
- P0404: Exhaust Gas Recirculation "A" Circuit Range/PerformanceMechanic Base · Other source · published 7 January 2023 · consulted 2 October 2026
- Desmontando mitos: ¿puede pasar mi coche la ITV con el testigo de «avería motor» encendido?Diariomotor · Motoring press · published 8 March 2021 · consulted 2 October 2026 · in Spanish