Error Code P0409 & P0403

[jmjosse]

Hey guys,

 

3 of our engine lights came on on our Outback Diesel so I hooked her up to the OBD2 reader.

the following codes popped up

P0409: exhaust gas recirculation position sensor performance

P0403: exhaust gas recirculation circuit.

 

I believe i need to replace my exhaust manifold/02 sensors.

 

Anyone had this problem before?

 

Any help or info would be a great help.

 

Thanks a lot,

 

JM

[Gambit]

I've just looked at the codes and I get 

 

Exhaust Gas Recirculation Sensor "A" Circuit
What does this mean?
OBD Code P0409refers to
The optical sensor provides a high resolution signal to the Powertrain Control Module (PCM) by counting pulses on the sensor disk located in the injection pump. The high resolution is one of the most important inputs by the PCM for fuel control and timing. This test monitors the number of high resolution pulses which have been missed (not detected). It's based on a comparison between the number of pulses that were detected since the last pump cam pulse and the number of the pulses that should have occurred. There are approximately 64 high resolution pulses for every cam pulse.
Symptoms
Possible sumptoms of OBD code P0409
- Engine Light ON (or Service Engine Soon Warning Light)
Causes
Possible causes of OBD code P0409
- Open or short in the optical sensor circuit - Optical sensor connector - Damaged optical sensor - Damaged PCM or ECM The Error code is generally activated on detection of the following conditions: Some high resolution pulses are missing from the optical sensor to the PCM
Possible Solutions
- If damage, repair optical sensor circuit - Replaced optical sensor - Replaced PCM or ECM

 

 

 

Exhaust Gas Recirculation Control Circuit
What does this mean?
OBD Code P0403refers to
The Exhaust Gas Recirculation (EGR) system is controlled by a vacuum solenoid. The solenoid is supplied ignition voltage. The Powertrain Control Module (PCM) controls the vacuum solenoid by grounding the control circuit(ground) or driver. The primary function of the driver is to supply ground for the object that is being controlled. Each driver has a fault circuit that the PCM monitors. When the PCM turns a component on, the control circuit voltage is low, or close to zero. When the component is turned off, the voltage on the control circuit is high, or near Battery voltage. The PCM watches for these conditions, and if it doesn\'t see the proper voltage at the proper time, this code is set.
Symptoms
Possible sumptoms of OBD code P0403
Usually a fault in the control circuit, will leave no noticeable symptoms other than the Malfunction Indicator Lamp (MIL) illumination. However, if the EGR control solenoid is stuck open due to debris, etc. the code may be accompanied by misfire under acceleration, rough idle, or engine dying altogether.
Causes
Possible causes of OBD code P0403
The causes for a P0403 EGR code could be any of the following: Bad EGR solenoid Excessive resistance in control circuit (PCM controlled ground) due to an open, chafing or damage to the harness Poor connection at the EGR solenoid harness (worn or loose pins) Water intrusion at the EGR solenoid harness Blockage in EGR control solenoid holding solenoid open or closed causing excessive resistance Loss of supply voltage to EGR solenoid Bad PCM
Possible Solutions
With the ignition on and engine off, use a scan tool to activate the EGR solenoid. Listen or feel for a clicking, indicating that the solenoid is operating. If the solenoid does operate, you'll have to check current draw on the ground circuit. It should be less than one amp. If it is then the problem is intermittent. If it isn't then there is excessive resistance in the circuit and perform the following 1. When it's activated see if you can blow lightly through it. IF you can\'t there may be a blockage causing excessive resistance. Replace EGR solenoid as needed. If there is no blockage, disconnect the EGR solenoid and the PCM connector containing the EGR solenoid control circuit. Using a digital Volt-Ohm meter (DVOM) check resistence between the control circuit and Battery ground. It should be infinite. If it isn't, then there is a short to ground on the control circuit. Repair the short to ground and retest as needed. 2. If the solenoid doesn't click as it should, disconnect the EGR solenoid connector and connect a test light between the two wires. Using the scan tool, command the EGR solenoid on. The light should light up. If it does, replace the EGR solenoid. If it does not perform the following: a. Check for 12 Volts on the ignition supply voltage to the solenoid. If it isn't present, inspect the supply circuit for an open, or a short due to chafing or breakage and re-test. b. If it still doesn't operate: then manually ground the EGR solenoid control circuit. The light should light. If it does, repair open in EGR solenoid control circuit and re-test. If it doesn't, replace EGR solenoid.
Related Codes
P0400 P0401 P0402

 

 

Hope that helps a little 

[jmjosse]

HI Gambit,

thanks for your time, research and reply.

 

What would my next step be now?

get a new Optical sensor?

 

Thanks,

JM

[Gambit]

Hi mate no worries. Yeah I would for the 1st error code. The 2nd I would try clean it all 1st and after you have changed the optical sensor reset the codes and see if it comes back. If it does looks like the solenoid would need replacing.

[jmjosse]

sweet, awesome.

 

Do you know the OEM parts numbers for the Optical sensor and solenoid by any chance?

And what the location of the sensor on the outback? is it easily reachable?

 

Thanks again

[David in Hampshire]

This is the thread that won't go away.

Gambit.  sounds great but imagine I don't know what or where this sensor is.  What do I do?

[David in Hampshire]

Got news for you lot.

Been into my Subaru main dealer and the parts guy assures me that there is no optical sensor.  We drew a map of where the gas goes and the mechanic told me that P0409 comes up when the motor in the EGR housing fails.  As far as Subaru is concerned, there is only one possible solution.

What does P0409 mean?  The valve is a disc that rotates on its vertical axis, like a coin.  This is enabled by a motor and I believe that the max open position is 70 degrees.  5 wires go into the EGR valve, one of which is 5v so don't fry it!  A pipe comes up off the exhaust, and the gasses flow through the EGR back into the engine in an effort to burn uncombusted fuel.  Yeah, I know, but this is how it's designed.  When the valve opens, the exhaust gasses flow.  The wider the opening, the more gasses.

The valve is closed when the engine is idling and when your giving it full throttle.  It is not dependent only on the vehicle speed or the revs of the engine.  The lower mark is engine revolutions and the upper mark is throttle position.  It opens by degrees of rotation depending on where the revs are and what the car is doing.  So if you've got your toes in the carpet then the valve is closed.  Capish?

Which means that if the failed EGR valve is stuck 'open' then the car is harder to start because the mix is too lean (too much air) but performs better under power because the mix is richer (close on the right amount of air for that amount of diesel).  If the valve is stuck 'closed' then it is easier to start because the mix is right but you lose power and have lower MPG whilst moving.  You can short the EGR out whilst the engine is idling and if it's operating then it will stall for this reason.  And if your valve is stuck in the wrong place then the Nox (Nitrous Oxide) reading may fail your MOT.

So if the valve is stuck, the electronics will still prompt the motor to operate the valve but as it's not going to move, the motor will eventually fail (burn out) and the EMU will throw a P0409 error code.  Your EGR valve is stuck and the motor is dead.  Resetting the fault code will not fix a burnt out motor.

What's the solution?  The fastest is to buy a new one.  Or you could buy a pattern part for a Nissan or Mitsubishi, dismantle the two and make one good one out of the bits.  What isn't going to help you one bit is any form of spray, seafoam or any other type of EGR cleaner because the part has already burnt out - you're trying to fix the wrong problem  And if it's seized in a 'closed' position then it's straight out the exhaust anyway, and if it's seized in an 'open' position then the motor is knackered anyway.  It is a spray, not a magic want.

The part number is 14710-AA740 but the last 5 digits change depending on if your looking at a Nissan Pathfinder/Navara (14710-EC00D).  Nissan can be found for just over £60 on eBay.  New Subaru are over £300.  The main difference seems to be the coolant pipes.

I'll buy a new part and do a 'how to'.  The PDF attachment is a Subaru parts map.

Laterz

dsc_0709.pdf

[Morphaldo]

Thanks for posting the above - i have had a re-occurring egr issue (P0409) for about 2 years now. Fitted a new EGR last year and its still throws errors.

Can reset the code and its fine, re-errors after a restart. Or disconnect the Battery and it goes away for two restarts, then returns.

Had an auto-elec come out and they recon the error is caused by a faulting temp sensor on the DPF - these seem to be about £150+vat each (there are 2..).

Going to try the swapping egr value again, buy a nissan one and swap the mech on top over as suggested - has anyone done this yet? The Nissan ones are £40 on eBay, so not a huge risk.

Alternatively would anyone know where I can get the codes for the EGTS from? (Exhaust Gas Temp Sensor). Its a 2ltr diesel boxer, 58 plate (Nov 08)

[David in Hampshire]

Hi Morph

Same engine as mine, but i'm in an Outback.  Yeah, resetting the ECU won't stop the notification of the fault.  If you do a swap-over then you'll need some very small security torx bits to get the top off.

As luck would have it, I have been in contact with the factory in China where these valves are made - the joys of the internet.  I have 10 brand new ones on their way to me.  Obvious when you think about it, really, car manufacturers don't make seats, they certainly don't make tyres and they don't make EGR valves either.  It's all from China.  Rumour has it that most Triumph motorbikes are made in Thailand, and then assembled in England.  As the advert says - "Vauxhall, a British brand since 1903".  Vauxhall are owned by Opel who are owned by Peugeot/Citroen.  Subaru EGR's appear to be made in China.

I was going to do a Nissan swap-over but thought, I can't be arsed.  So when they arrive i'll do another 'how to' and all going well, you can have one of these new ones.

[Morphaldo]

Thanks David - can you PM how much? I have the tools for the swap over -and the one I have in now came from a seller who imports from China. Dont have an issue with that, it why consumables are now so cheap, and disposable! Best for us all. 

 

[David in Hampshire]

Fixed it,

You can read the how to thread here.

 

[Mr B]

The egr has inbuilt position reference that part of the logic of how ecu knows it failed, unless parts guy examined a egr or read the fault logic criteria he ain't going know that, pinout and code criteria data will show you exactly how it controlled and monitored by ecu .

[David in Hampshire]

Just taken one apart, Mr B.  IMHO, this unit fails totally, and not by increment.  One write up to follow!

[Mr B]

Seen them fail in various ways, sometimes motor runs but drive failed, sometimes seized, sometimes carbon build up stops it seating fully or opening full range.
All of which can be detected by the ecu monitoring and can flag the money light if code criteria match to ecu received sensor/conditions data .

Generally new egr only way go, sometimes you can clean them but we only tend do that as a quick fix during diagnosis so owner can carry on like normal until job booked in or part delivered .
egr is a consumable product due to harsh job it does, It's true value in emission and environment impact is somewhat overestimated as it has negative effect engine lifespan, mpg and service parts waste during a vehicles life, much like the dpf while making nice numbers at tail pipe under test conditions if review exactly how it achieves that and the negatives it has on reducing mpg/power and increasing parts/service waste over vehicle lifespan it a long way from environment marvel .

[Morphaldo]

On 1/31/2019 at 9:37 PM, Mr B said:

The egr has inbuilt position reference that part of the logic of how ecu knows it failed, unless parts guy examined a egr or read the fault logic criteria he ain't going know that, pinout and code criteria data will show you exactly how it controlled and monitored by ecu .

2 concurrent issues.

1. Traced back to a faulty EGTS, part number and photos below if needed. That was not reading over 160Deg, so the DPF never reached temp to do a reg-gen which then caused over-sooting, and a flashing light on the dash. Readers will show you the two sensors, and you can see them increase as the DPF gets hotter - my faulty one is the center front on the DPF, not the one to the left. (boxer SH 2.0ltr engine).

2. Error (P0409) caused by a faulty EGR ("...P0409 comes up when the motor in the EGR housing fails.  As far as Subaru is concerned, there is only one possible solution) - so replaced the EGR (cheers @David in Hampshire). Hasn't fixed it. Bugger. Still get the 2 lights every two engine start cycles. Tried resetting, diconneting the Battery and pressing the horn, draining all residual power etc, leaving over night disconnected, etc etc.

The EGR is working as you can hear it setting, however its reading a -7Deg when closed, was expecting that to be 0Deg. No idea why this would be, or how to resolve. what a nightmare!

 

[Crampy]

Hi Morphaldo,

Did you ever manage to sort this problem?

I've just put a new EGR on my 2008 legacy 2.0d due to getting recurring P0409 code.

Still getting the code as well........

[Subaru1990]

On 21/5/2019 at 12:39, Crampy said:

Ciao Morphaldo,

Sei mai riuscito a risolvere questo problema?

Ho appena inserito un nuovo EGR nel mio 2.0 legacy 2008 grazie al codice P0409 ricorrente.

Sempre ottenendo il codice pure ........

solved??

[diavlo1984]

There is a recurring theme I am finding.  As a fellow Subaru Diesel owner with the P0409 problem on engine start, having already replaced the EGR valve,  what is going on?   Someone must know how to fix this as its not going to pass its MOT as you can clear the code, and then it comes back.  I do get a hissing sound, but we've checked everything is tight and can't find any leak on intake.  Could it be the exhaust cooler leaking, could that cause a P0409?

[Steve Webb]

Did anyone ever find the true fix for this 409 code? Because I've put 2 brand new egr valves on and the code comes back after about an hour of resetting! Find it difficult to believe I've got 2 faulty new ones.

[Thomas0404]

Did anyone find out the solution to this problem I have exactly the same issue, replaced egr valve and still get the lights, my car needs an mot but it won't pass with these lights on

[Kamillo]

Hi, did anyone find solution to this problem? I have the same problem after replacing egr.

[Kamillo]

Hi, replacing egr valve for original one solved the problem. NTY valve was the problem. Cheers.

[___ian___]

After replacing an EGR with a new EGR you must perform a EGR angle learning, so the ECU can learn the voltages from the position sensor that represents 0 degrees. If the ECU doesnt relearn the new position sensor, when the engine is turned off it will detect a fault (you can hear the ECU testing the EGR when you turn the engine off). If it detects a mismatch 2x in a row it will throw a P0409. Clearing the P0409 code gives you 2 more goes but it will always come back without EGR angle learning.

3 options to fix (assuming no other codes and no wiring faults)

1. Clean the original EGR, open it up fix anything that stuck, stiff or broken, but keep the sensor the same.
2. Take the top of the original EGR and put it on the new EGR, hoping that the magnets indicating angle are in exactly the same position. (cheap(er) eBay replacements use different sensors and internal design even though the part numbers match)
3. Get someone (main dealer) with a Subaru Select Monitor to perform the EGR compulsory learning operation. (search follow the installation on EGR here http://jdmfsm.info/Auto/Japan/Subaru/Legacy_Outback/2008/Legacy 2008/index.html)

There are 2 other options for the really persistent DIYer.
Keep replacing the EGR till you strike it lucky and get one that matches perfectly.
Really take the EGR apart and get the 0 degree voltage to match by moving the magnets on the valve shaft.

 

If anyone knows of a scantool operation that will do the reset please say. Disconnecting negative for 30min doesn't do an EGR angle learning reset.

I expect my EGR will break again and would love to know the dark magic to do it.