|Code||Fault Location||Probable Cause|
|P1404|| P1404 – Exhaust Gas Recirculation Closed Position Performance (Buick, Cadillac, Chevrolet, GM, Pontiac, Saturn) |
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Manufacturer Specific Definitions for P1404
|Acura||EGR Valve Stuck Closed|
|Audi||Exhaust gas recirculation (EGR) system - basic setting|
|Bmw||Camshaft Position Actuator 'B' Control Open Circuit Bank 1|
|Buick||Exhaust gas recirculation (EGR) valve -not fully closing|
|Cadillac||Exhaust gas recirculation (EGR) valve -stuck open|
|Chevrolet||Exhaust gas recirculation (EGR) valve not fully closing|
|Chrysler||Exhaust gas recirculation (EGR) valve position sensor malfunction|
|Citroen||IAT - B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance|
|Daewoo||Exhaust gas recirculation (EGR) valve – range/performance problem|
|Dodge||Exhaust gas recirculation (EGR) valve position sensor malfunction|
|Ford||EGR Valve Stuck Closed|
|Gmc||Exhaust gas recirculation (EGR) valve -not fully closing|
|Gm||EGR Valve Closed Position Performance Conditions|
|Honda||Exhaust gas recirculation (EGR) valve - valve closed|
|Hyundai||DMTL Heater Circuit Malfunction|
|Isuzu||Exhaust gas recirculation (EGR) valve – stuck open|
|Jeep||Exhaust gas recirculation (EGR) valve position sensor malfunction|
|Kenworth||P1404 - CCVCD fault if pressure sensor reading deviates too much from expected value at key on|
|Kia||Evaporative emission (EVAP) leak detection module heater – circuit malfunction|
|Land Rover||Pressure transducer – metering orifice restricted|
|Mahindra||Egr Valve Jammed At Closed Position 243-245 Sr. No. Description Page No.|
|Mitsubishi||EGR Position Sensor Rationality Closed|
|Oldsmobile||Exhaust gas recirculation (EGR) valve -stuck open|
|Opel||Exhaust gas recirculation (EGR) valve - range / performance problem|
|Peterbilt||P1404 - CCVCD fault if pressure sensor reading deviates too much from expected value at key on|
|Peugeot||IAT - B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance|
|Pontiac||Exhaust gas recirculation (EGR) valve – not fully closing|
|Ram||Exhaust gas recirculation (EGR) valve position sensor malfunction|
|Saturn||Exhaust gas recirculation (EGR) valve, stuck open|
|Suzuki||EGR Closed Valve Pintle Error|
|Volkswagen||Exhaust gas recirculation (EGR) system - basic setting|
What Does Code P1404 Mean?
SPECIAL NOTES: OBD II code with the definition “IAT [Intake Air Temperature] – B Circuit Malfunction / Exhaust Gas Recirculation Closed Position Performance” is mostly relevant to some General Motors (and a few European) products from the late 1990’s to the early / mid 2000’s, and is therefore no longer in common use by most manufacturers. Starting in the mid-2000’s, the “IAT [Intake Air Temperature] – B Circuit Malfunction” component of the definition was dropped, largely due to improved PCM programming, even though it still appears in many sources, including online lists of OBD II code definitions.
However, the transition from the definition “IAT [Intake Air Temperature] – B Circuit Malfunction / Exhaust Gas Recirculation Closed Position Performance”, to the definition most commonly used by many manufacturers for OBD II code P1404 today, “EGR Valve Closed Position Performance”, has NOT been smooth and/or uniform across all manufacturers, and it may still be encountered on older USDM applications and some European imports. The General Motors TSB below that describes a potential cause of this code on some older GM applications with the definition “IAT [Intake Air Temperature] – B Circuit Malfunction / Exhaust Gas Recirculation Closed Position Performance” is reproduced from official GM sources. Note that the “electronic noise” referenced in the TSB often originated in the Intake Air Temperature sensor.
– START OF TSB #86-65-03A
THIS BULLETIN IS BEING REVISED TO CORRECT APPLICATION INFORMATION FOR CALIBRATION P/N’S 09364726 AND 09364733 AND ADD THE ISUZU HOMBRE MODEL. PLEASE DISCARD CORPORATE BULLETIN NUMBER 86-65-03 (SECTION 6E – ENGINE FUEL & EMISSION).
SUBJECT: OBD II DIAGNOSTIC TROUBLE CODE (DTC) P1404 (REFLASH VCM)
MODELS: 1998-*99 CHEVROLET AND GMC C/K, M/L, S/T**, G, P MODELS 1998 OLDSMOBILE BRAVADA 1998 ISUZU HOMBRE WITH 4.3L, 5.0L, 5.7L OR 7.4L ENGINE (VINS X, W, M, R, J – RPOS LF6, L35, L30, L31, L29)
*(C/K, G WITH RPO ZK3) **(DOES NOT INCLUDE RPO ZN4)
SOME VEHICLES MAY SET A FALSE OBD II DTC P1404.
ELECTRONIC NOISE IN THE VEHICLE MAY CREATE MOMENTARY FALSE “LOW” EXHAUST GAS RECIRCULATION (EGR) PINTLE POSITION FEEDBACK SIGNAL VALUES. SEVERE OCCURRENCES MAY CAUSE THE VEHICLE CONTROL MODULE (VCM) TO SET A P1404 DTC BECAUSE THE VCM PERCEIVES THAT THE EGR VALVE IS STUCK OPEN.
1. USING THE TECH 2 SCAN TOOL, EXERCISE THE EGR VALVE, AND VERIFY THE [EGR] VALVE’S ACTUAL AND DESIRED POSITION TRACK.
2. FOLLOWING STEPS 1, 2 AND 3 OF THE STRATEGY BASED DIAGNOSTICS, DETERMINE IF THE VEHICLE HAS AN ACTUAL EGR VALVE CONDITION. IF THERE IS A VALVE CONDITION, PERFORM THE APPROPRIATE REPAIR PROCEDURES.
3. FINALLY, REFLASH THE VCM WITH THE NEW SOFTWARE AND CORRESPONDING CALIBRATIONS LISTED BELOW. THESE NEW CALIBRATIONS ARE DESIGNED TO MAKE THE DTC LESS SUSCEPTIBLE TO NOISE.
OLD P/N NEW P/N APPLICATION ——- ——- ———– 16263425 09365095 ALL VEHICLES WITH RPO’S L35, L31, L30, L29
In light of the above TSB it is highly recommended that when OBD II code P1404 with the definition “IAT [Intake Air Temperature] – B Circuit Malfunction / Exhaust Gas Recirculation Closed Position Performance”, is encountered on any vehicle, and specifically GM products that are older than about 10 years, the authorized dealer be contacted to verify that the PCM had been re-programmed with upgraded software. END OF SPECIAL NOTES.
OBD II fault code P1404 is a manufacturer specific code that is defined by General Motors (Chevrolet in particular) as “Exhaust Gas Recirculation (EGR) Closed Position Performance”, and is set when the actual position of the EGR valve pintle does no coincide with the position of the EGR valve pintle the PCM (Powertrain Control Module) is expecting to see when the EGR valve is closed. Note that this code is primarily concerned with the position of the EGR valve pintle at start-up, as opposed to general issues with the amount of recirculated exhaust gas in the system at any given time.
NOTE: This guide will focus only on “Linear (Electronic) EGR Valves”, which is the type of EGR valve most commonly used on applications dating from the early 1990’s to the present. To avoid confusing definitions of code P1404, refer to the “Related Codes” section of this guide for details on other definitions of code P1404 that may or may not relate to the EGR valve pintle position. Since many manufacturers use variations of the definition for this to indicate EGR valve control related issues, it is strongly recommended to always consult the manual for the application being worked on to determine the exact definition of code P1404 as it relates to that application.
In terms of operation, Linear Electronic EGR valves incorporate a position sensor that relays the position of the valve pintle to the PCM. This information is based on changes in a signal voltage that ranges from about 0.1- 0.3 volt when the valve is closed, to about 5 volts when the valve is in the fully open position. In practice, the PCM “learns” the value of the “valve closed” signal voltage when the electronic circuits on a new vehicle are activated for the first time. This value is retained in the PCM as a reference value, against which subsequent “closed-position” values are compared every time the ignition is switched on.
Thus, when the PCM receives a value that exceeds the “learned” value for a specified time, or number of times, a code will be set, and a warning light illuminated. However, the setting parameters of this code are not uniform across all applications. Always consult the manual for the application being worked on for detailed information on the code setting parameters for that application.
During normal operation, the PCM determines the amount of exhaust gas required at any given time based on information gathered from several sensors scattered around the engine and exhaust system. Based on this operational data, the PCM controls the opening and closing of the EGR valve by feeding a changing voltage signal to the EGR valve stepper motor, which movement is confirmed by the EGR valve position sensor via a return voltage signal to the PCM.
Regardless of its design and control system though, the primary purpose of the EGR valve on any internal combustion engine is to allow a certain percentage of the total exhaust stream to be mixed with the incoming air/fuel mixture. The object is to reduce combustion temperatures to below about 1 5000F (8000C) to prevent, or reduce the formation of various oxides of nitrogen, which are the principal components in exhaust gas that forms smog. In gasoline engines, the percentage of recirculated exhaust gas typically varies between 5% and 10%, depending on operating conditions, while on diesel engines this percentage can be as high as 50% under certain conditions.
In all cases though, exhaust gas is not recirculated (EGR valve is kept closed) during idling, or when the engine is under a heavy load. In both cases, engine efficiency depends on complete combustion of the air/fuel mixture, which is influenced negatively when exhaust gas is introduced into the engine. Exactly when, how, and how much exhaust gas is recirculated at other times depends on the application, and the particular operating conditions that obtain at that particular moment.
Also, note that the VVT/VCT systems found on many modern engines obviate the need for exhaust gas recirculation on these engines, since altering valve timing, valve lift, and/or valve overlap and duration has the same quenching effect on combustion temperatures as EGR.
The image below shows the basic construction and operating principles of a typical linear (electronic) EGR valve. Note however that the design, appearance, location, and other details of linear EGR valves differ greatly between applications.
What are the common causes of code P1404?
By far the most common cause of this code is carbon build-up on the pintle and its seat that prevents the valve from closing fully. Other possible causes could include the following-
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors.
- Open circuits.
- Defective EGR valve.
- Excessive wear of moving parts of the EGR valve.
- Failed, or failing PCM. Note that this is a rare event, and the fault must be sought elsewhere before any controller is replaced.
What are the symptoms of code P1404?
In some cases, code P1404 may have no symptoms other than a stored trouble code and an illuminated warning light. Other symptoms are mostly make and model specific, but note that the severity of one or more symptoms may vary greatly between applications. Nonetheless, typical symptoms could include the following-
- Loss of power that can vary from slight and barely detectable, to severe enough to immobilize a vehicle.
- Rough or erratic idling that can vary from slight to severe.
- Frequent or unpredictable stalling.
- Hard starting.
- Detonation (pinging or knocking) upon acceleration, or when the engine load increases.
- Increased fuel consumption.
- Increased levels of nitrous oxides and other harmful emissions in the exhaust stream.
- In some cases, black smoke may be visible from the tail pipe, particularly on diesel applications.
NOTE: This list of possible symptoms is not exhaustive or complete. In addition, not all, or even most of the possible symptoms listed here will always be present on all applications. Hence, the absence of one or more symptoms listed here has no diagnostic value in itself.
How do you troubleshoot code P1404?
NOTE: As stated elsewhere, this guide focuses on issues with the pintle position on linear EGR valves at start-up, as opposed to general EGR system defects/malfunctions. Therefore, the diagnostic and repair procedures outlined here do not apply to EGR valves that are controlled by vacuum or exhaust back pressure. Consult the relevant manual for detailed information on the correct diagnostic procedures and repair options for these types of EGR systems.
Record all fault codes present, as well as all available freeze frame data. This information can be of use should an intermittent fault be diagnosed later on.
NOTE: At the risk of overstating the case, confirm or verify that code P1404 applies to the linear EGR valve on the application being worked on before proceeding with the diagnostic procedure.
Switch the ignition to the “ON” position, but do not start the engine to establish the EGR valve ground circuit. The scanner will indicate the EGR valve pintle position as a voltage value, which should be about 0.1 volt, to 0.3 volt, depending on the application. Consult the manual for the exact value for the application being worked on.
Bear in mind at this point that the PCM is comparing the “learned’ value with the actual position of the EGR valves’ pintle. When the difference between the actual and “learned” positions varies by more than a predetermined value, or for longer than a specified period, code P1404 will be set. Thus, if the difference displayed on the scanner does exceed the allowable difference, the cause is as likely to be a physical obstruction such as carbon deposits on the pintle or pintle seat that prevents the valve from closing fully, as it is to be a wiring problem.
Carbon build-up is a common cause of this code, and especially on applications that are known for their high rates of oil consumption such as BMW, Audi, Mercedes-Benz, and most VW products.
One way to check if this is the case is to command the EGR valve fully open with the scanner, at which setting the displayed signal voltage should be 5 volts, or very close to it. Provided the pintle can move freely, the increase in the displayed voltage should be smooth, without “glitches” or interruptions. If the signal voltage rises smoothly, it is unlikely that the cause is related to wiring.
Note that commanding the EGR closed may not result in the same difference between the “learned” and actual positions of the valve pintle because the obstruction or object that prevents the valve from closing fully may have moved. Nonetheless, if the scanner shows that the EGR valve is moving freely, prepare to remove the EGR valve from the engine to inspect it for the presence of carbon deposits.
If however, the scanner does not indicate a change in the signal voltage when the EGR is commanded open, or if the signal voltage “sticks” at any point between the closed and fully open position, consult the manual to determine the location of the EGR valve, as well as the location, function, color-coding, and routing of all associated wiring.
Perform a thorough visual inspection of all associated wiring and connectors, and look for damaged, burnt, shorted, and/or corroded wiring and connectors. Make repairs as required, clear all codes, and rescan the system to see if the code returns. Note that on some applications it may be required to complete several drive cycles before the code can either be cleared, or be cleared automatically by the PCM. Consult the manual on this point.
During the inspection of the wiring, disconnect the EGR at the connector. The indicated signal voltage should be zero; if it is higher, the signal wire is likely to be shorted to power. If this is suspected, prepare to perform resistance, ground, reference voltage, as well as continuity tests on all wiring. Be sure to consult the manual on the correct procedure(s) to follow during step, and be sure to disconnect the EGR system wiring from the PCM during this step to prevent damage to the controller.
Note that the EGR valve forms part of the control circuit, and as such, its internal resistance(s) must be tested and checked against the manufacturer’s specifications as well.
Compare all obtained readings with those stated in the manual. If discrepancies are found, make repairs as required to ensure that all electrical values conform to the manufacturers’ specifications. Clear all codes after repairs are complete, and rescan the system to see if the code returns. Refer to Step 4 with regard to clearing the code.
Refer to Step 3
If no visible damage to wiring is found and all obtained electrical values agree with the manufacturers’ specifications, but the code persists, prepare to remove the EGR valve from the engine. Note that on some applications this step may involve some disassembly of other, unrelated components, so always consult the manual on the correct procedure to remove the EGR valve to prevent damage to other components.
NOTE: Not all EGR valves can be cleaned to remove carbon and other deposits. On some applications, the assembly is sealed and the only remedy is replacement of the EGR valve. Other possible issues involve wear of moving parts that can influence the valves’ settings.
Bear in mind that EGR valves are not expensive, and that in almost all cases it is possible to replace a defective or clogged-up valve on a DIY basis, although integrating the replacement with the PCM might have to be done professionally. This should be weighed against the fact that-
- the vehicle will not pass a mandatory emissions test unless the valve is replaced or returned to working order,
- and that serious driveability issues might develop unless the EGR valve is replaced.
WARNING: If it is possible to clean out the EGR valve, use ONLY approved solvents, and make absolutely sure that no dissolved carbon enters either the stepper motor, and/or the solenoid assembly. Apart from possible causing short circuits, dissolved carbon can prevent movement of moving parts once the solvent evaporates.
Once repairs to, or replacement of, the EGR valve is complete, consult the manual on the process of integrating the repaired/replaced valve with the PCM, that needs to “learn” the new closed position signal voltage. With some luck, this voltage may be within the range specified by the manufacturer, but it happens more often than not that aftermarket EGR valves do not meet the required range.
If the scanner has programming functions (and the correct software is available), it might be possible to adapt the PCM to the new EGR valve on a DIY basis, but DO NOT attempt this procedure unless you have a complete understanding of what it is you are reprogramming. If you are not comfortable with reprogramming your vehicle, or if the required equipment/software is not available, the better option is to refer the vehicle to have the adaptation performed professionally.
If the code returns after replacing/cleaning the EGR valve, there are a few possible causes to consider-
- The EGR valve pintle still does not close fully after the cleaning procedure. (Replace the EGR valve.)
- The replacement EGR valve’s pintle position generates a signal voltage in the closed position that falls outside of the allowable range. (Replace the EGR valve with an OEM part.)
- The replacement EGR valve is not properly integrated with the PCM. (Repeat the integration process.)
- There is an intermittent fault present. Note that intermittent faults are sometimes extremely difficult and time consuming to find and repair. In some cases, it might be necessary to allow the fault to worsen before an accurate diagnosis and definitive repair can be made.
Codes Related to P1404
Apart from BMW that defines code P1404 as “Heated Catalyst Current – Too High during Heating (Bank 2)”, many other manufacturers have assigned specific EGR valve related issues to P1404. Below are some examples, but to prevent misdiagnoses and wasted time, it is strongly recommended that the exact definition and meaning/application of code P1404 be properly researched whenever code P1404 is encountered on any application.
- Acura – EGR Stuck Closed
- Chrysler/Dodge/Jeep – EGR Close Position Performance
- Citroen/Peugeot – IAT (Air Intake Temperature) – B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance
- Fiat – Circuit TL4226
- Ford – IAT (Air Intake Temperature) – B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance
- GM – Exhaust Gas Recirculation (EGR) Closed Position Performance
- Isuzu – EGR Valve Stuck Closed
- Lincoln – IAT (Air Intake Temperature) – B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance
- Mercedes – EGR control
- Mercury – IAT (Air Intake Temperature) – B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance
- Oldsmobile – IAT (Air Intake Temperature) – B Circuit Malfunction/ Exhaust Gas Recirculation Closed Position Performance
- Opel – Exhaust gas recirculation (EGR) valve – range / performance problem
- Saturn – EGR Closed Position Error (1997)
- Volkswagen/Audi – EGR Flow Basic Setting not carried out
- Volvo – EGR Flow Basic Setting not carried out
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