Exhaust Gas Recirc Valve on the NC Engine

I have a DTC (PO403) advising a posible EGR problem on my Mk 3. Has anyone removed the EGR from the NC engine? Looks tricky. Any tips?

Yes, it’s tight. Remove the wipers and scuttle panel for better access. There is a metal access plate that can be removed too. There is a special tool which is a funny shaped spanner to improve access to the bolt but I can manage it with the sockets that I have. You’ll have to see what you have that you can get onto the bolts with. From experience it’ll be a failed valve.

Thanks for the comments.

I went ahead with this job and the following notes may help others. I’m a relative newbie and couldn’t find any information on this on the site so apologies if it is covered elsewhere. The EGR Valve is very difficult to access and a Mazda special tool (or home made equivalent) is essential to remove and refit the EGR Valve.

The Mazda NC MX5 Manual can be downloaded from the Internet and will prove useful. Try http://www.mellens.net/mazda/index.html . Note that most Internet manuals seem to be for Left Hand Drive vehicles and there will be detail differences on UK models (such as in this activity no heater hoses to remove and a different shape harness bracket).     

  1. Disconnect the battery.
  2. Lift off the spark plug cover.
  3. Remove both the windscreen arms. Remove the rubber bungs and nuts and pull off the arms. A small puller may be required as there is nothing substantial to lever against.
  4. Drain the water from the radiator.  However, assuming you have a RHD MX5 the water loss when disconnecting the EGR will be small as it is not necessary to disconnect the heater hoses provided the expansion tank cap is kept on.
  5. Remove the cowl grilles behind the windscreen wipers.  ‘T’ shaped plugs hold the weather seal and cowl grilles in place. Remove the weather seal completely. Remove the two plugs and crosshead screws in the cowls below the windscreen. Pull the cowls forward to release the clips. Then disconnect the windscreen washer hoses at the nearest connections and remove the cowls from the car.
  6. Remove the side cowl grille. This is on the passenger side and held in by several trim panel clips which unlock if turned.
  7. Unclip the two pipes from the Service Hole Cover. These are for the brake servo and air conditioning refrigerant.
  8. Remove the Service Hole Cover Plate.  Held on by eight 10mm bolts.
  9. Remove the Harness Bracket at the back of the cylinder head.   Remove the earth connection bolt first, followed by the bracket bolts. Remove any sockets and cable clips to completely free the Harness Bracket.
  10. Improve EGR Valve access.   Push the heater hose to one side and any wiring which obstructs access to the EGR Valve. Press the release button and pull the EGR Valve electrical connector away.
  11. Remove EGR Valve. You should now be able to see the top of the EGR Valve. Remove the small bore cooling hose clip and hose. Plug the hose to minimise coolant loss. The EGR is held on by two bolts which are barely visible. Access is very restricted and the forward angle of the scuttle means that conventional spanners or sockets will have problems getting near. I managed to remove the passenger side bolt using my longest 10 mm combination spanner with a suitable bit of tubing as an extension. This wouldn’t work on the other side due to other items obstructing access. I finally bent an old cheap 3/8 inch ratchet spanner by cutting a notch with an angle grinder near the middle and bending it towards the socket with a large hammer.
  12. Dismantle EGR. Hold the EGR valve securely and remove the four set screws. These may be tight. The top lifts off in one piece (no springs etc will fly out). Clean the lower part of the valve using carburettor cleaner or brake cleaner (not brake fluid).  Check movement is free by pressing the spring.
  13. Stepper Motor check.  Check the resistance at the Stepper Motor terminals. There are two rows of three terminals. In each group of three check that the resistance between the centre terminal and each of it’s two adjacent terminals is 12 to 16 ohms. If you’ve had a PO403 Fault Code the fault may lie here.
  14. Replacement Mazda EGR Valves. A replacement Mazda EGR Valve from mx5parts.co.uk will cost £237.70 including VAT plus £9.95 delivery. The valves are only available as a whole and replacement stepper motors do not seem to be available.
  15. Alternative EGR Valves. The Mazda MZR engine is fitted to several other cars such as the Mazda 6, Mondeo Mk3, Volvo V40 and others. Many parts are identical. Petrol Mondeos are fairly common and I note that new Mondeo EGRs can be bought for £77 on e-bay. Alternatively Mondeos are plentiful in scrapyards (and the EGR is relatively easy to remove). I bought one from a Mazda 6 for £20. The only differences between the MX5 EGR and the Mazda 6 / Mondeo EGRs are that the stepper motor is rotated through 90 degrees (easily moved) and the water cooling pipe is shorter on the MX5. The water pipe or hose can easily be modified in one of several ways but make sure the hose is clear of the EGR pipe. I also own a Mondeo so was able to swap stepper motors over to confirm that they are the same. (In so doing I transferred the DTC to the Mondeo confirming that the stepper motor was faulty). My valve was clean and operating freely but the Stepper Motor was faulty so I re-used the MX5 EGR body. The gasket is also available from Ford (Part No 1355115) if the Ford garage is nearer to you.
  16. Replacement.  I found it slightly easier to fit the Stepper Motor after the EGR was bolted in place. Check the gasket is still in place before you tighten the EGR bolts. I tied mine on with cotton through the bolt holes. Otherwise replacement is the reverse of removal. On re-test the DTC code has now cleared.

I had the same error code come up on my 2010 1.8 over the weekend.  Removing the whole EGR sounds like a pain - I don’t have the tools to bend an old spanner.

I was wondering whether it would be feasible to follow the steps below down to 11 but at that point just remove the stepper motor from the top of the EGR and replace it with one from a cheap Mondeo EGR.  For example from here.

Any tips very much appreciated!

Yes, that should be OK.

Mines done this twice now.

On both occasions, it’s been after being stood for a long period.


eg: It’s inuagural run out after winter, it was fine on the outbound journey.

When I started the car for the inbound journey, the MIL lamp came on.


The second occurance was a similar scenario, ok on the outbound journey and came on after being stood a few hours.


It’s on my list of jobs to do, if the situation becomes worse. In the meantime, I’ll carry the code reader and reset twice per year.

Reading between the lines, and after lots of googling, it looks like a mondeo one will fit, although it may need some work doing on the pipre and the top cap/stepper rotating.

The Mondeo one is about £25 vs £150 for the MX5 one.

Also from what I can gather reading the sticky thread, it may even be possible to change the stepper, with the egr in situ, which is always worth a consideration before swapping the whole valve.

Just to bump this one up again as I found it very useful when I got code P0403:

Got a Mondeo EGV (1.8 Petrol) from ebay for £19.99 delivered. As advised above it is a bit of a pain. In the end after seeing the position of this awkward bolt (and unsuccessfully remodeling a spanner) I decided to just replace the top (stepper motor). This worked fine, the code has gone so I would say dont bother with replacing the whole valve if you get this code.

One thing to mention I had to take the wiper motor and arms off as there is a plastic mount on it that stops you getting square on one of the screws on the stepper motor. Before taking this off I managed to ruin the screw head and ended up using a chisel to tap a new groove in the screw!

So its a pain but easy enough to do

My light came on again this week.

Similar scenario as my previous post.

AS resetting the ECU seems to fix it for a year, I’ve done nothing with mine as of yet.

Thanks gents for your detailed posts. My engine management light has been on for almost two years but i now understand it is an MOT failure so i thought i would address it. I went down the Mondeo route and just replaced the stepper motor. A bit difficulty and fiddly to get at and was very worried about rounding the screw heads but i managed to get it off and now all good. Engine management light was out when i restarted. The mazda dealer quoted my just over £500 and i paid 29.99 for a Mondeo EGR valve. All sorted so well happy. 

Came on again yesterday, so that’s twice this year.

Same scenario, was OK on my way to work.

8 hours later, 100 yards in to my homeward journey and it came on again.


I’ve now ordered an EGR valve with a view to changing the stepper this weekend.


last year my eml would come on shortly after starting the engine but only on a warm engine, never on the first start of the day. Using a scan gauge I would read and cancel the code ( EGR valve each time ) and the light would stay out until the next warm start.

just before it’s MOT test last year I did a couple of longer runs and I haven’t had the problem since! Bl66dy lucky I guess. 




On my NC, twice recently, after short journeys, the engine warning light came on. Fault code reader showed EGR, so I ordered a s/h one off ebay (for £46). Reset warning light and it hasn’t come on since.

I’m hoping the valve will be here for the weekend.

I’ll take a series of photos during the stepper swap and post up somewhere.

My EGR valve arrived on Saturday so I set about swapping just the stepper on Sunday morning.

It’s a pig to get to, in the respect that there’s a whole host of stuff to remove first, wipers, scuttle panel, brace bar, and access cover.

It’s right in the middle at the back of the engine, so it doesn’t take long to get back ache.

Disassembling everything to gain access to the valve took me about 40 minutes.

One of the screws holding down the stepper is easier to get to if you move the wiper assembly out of the way (2 bolts, 1 nut), and I found them easier to get to with the bonnet down

Like BigMac, I found the screws on the stepper quite tight, I had to shock the one under the wiper assembly with a punch to loosen it off.


Regarding the mechanical side of the valve, it’s a spring loaded plunger, the stepper motor pushes down on the plunger to operate the valve.

Before fitting the new stepper, it’s worth checking the operation of the plunger. Mine moved freely (like the new valve), so at this stage I’m going to assume that the fault is with the stepper.

Although my fault was intermittent, and I guess I can’t yet be confident that the problem is solved as it only came on about twice per year.

Incidentally, the old stepper measured out at 14.2ohms across the pins, but as an intermittant fault, it may not be in a fault state at the moment.

I ought to have measured the new one really.


Re-assembly took about 30 minutes.


Hi There, first post, just wanted to add another success story to the “you only need to replace the stepper motor” solution.

My newly bought 2007 Z-Sport was throwing the P0403 EGR Circuit code despite only 29K miles, and doing so extremely reliably the SECOND time it was started after each clearing of the code. Which is obviously why the light wasn’t there on my test drive!

I was quoted the better part of £500 for the fix, including the Mazda part and a lot of labour, (“we’ll need to drop the whole engine block”) so despite not having messed around with cars for some decades (though I did a fair bit in my youth) I set about replacing the stepper motor.

A few points to add to the other brilliant advice on this thread, for the benefit of other novices like me contemplating this job:

  • it worked - replaced the stepper motor and the code is now gone.

  • I’d misunderstood from the description where the access hole is - it’s just the top bit of the bulkhead immediately behind the top of the engine block, and “just” gives enough room for thin fingers to prod around.

  • a cheap 1/4" socket set with screwdriver bits is all I needed, but it did take me nearly three hours altogether. But I’m completely unpracticed at this so typically should take half that.

  • EGR valves for Ford Mondeos are identical other than the bent pipe - which will need modification if you replace the whole valve but the stepper motor is identical and a straight swap.  https://www.ebay.co.uk/itm/EGR-VALVE-FIT-FORD-MONDEO-MK3-1-8L-2-0L-PETROL-2000-2007-1119890-1S7G-9D475-AG/152748164542 was £29.95 . 

  • It is incredibly easy to strip the rear passenger side screw-head, as others have reported. Even if you don’t think you need to, I’d recommend removing the wiper motor for better access. When all else failed I had to drill mine out - hence the three hour job.

  • It is also incredibly easy to drop screws and screwdriver bits down into some recess of the engine under the valve, where you will have no hope of retrieving them without picking up whole the car, turning it upside down and giving it a bit of a shake. So I learned to use gaffa tape to hold screw to bit to flexible extension bar etc.

  • You actually get better access to some screws from the driver side going in behind the bonnet - with the wiper motor out of the way.

  • I didn’t have to move any water pipes, but there is a horribly positioned bit of wiring loom. I found this could be unclipped by pulling the clip vertically upwards - the clip is a kind of press-stud.

  • Make sure the valve itself moves freely once the stepper motor is off - assuming it does you can probably be confident the stepper motor will fix it. Once you have the new Mondeo valve in hand its easy to see how it works.

  • The little plastic covers on the scuttle cover will break when you refit them. 

  • You’ll have a DSC engine light when you start up and the skiddy tires light, these are normal and will clear when you do the steering-wheel-lock-to-lock thing and restart a few times.

So in summary it’s a really rotten job and you’ll have cuts on your hands, but its entirely doable even for a confident novice - it’s only nuts and bolts - though I honestly would not have wanted to try and get the whole valve out. But the stepper motor from a cheap Mondeo valve will save you hundreds of pounds compared to getting the Mazda EGR valve fitted in a garage, and is well worth a try if you have the P0403 code. 

Hope this is of some use, thanks for the advice on this thread.





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An excellent thread this - perhaps should be made sticky or whatever the acceptable terminology isSmile

Summarises a very common issue with the MK3 together with the best explanation of the actual problem and effective and cheap solution. I actually found the Mondeo unit with stepper for less than £20 on ebay

This appears to be a right of passage job for the MK3 rather akin to the cambelt/waterpump replacement on the MK1 - MK2.5.

A good opportunity for the keen owner to take some control and save a lot of money.     

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I did exactly that which solved the problem, you don’t need to drain coolant to do this.

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As a mk3 owner this is a really useful and informative topic.
Any thoughts on whether it would help to change the 4 cross head stepper motor retaining screws for an allen key type socket head while doing the job ? I was thinking this may or may not make removal and replacement easier

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If you’re going to do that, why not use stainless??
Stainless is tougher, so less likely to round out.
Also, it’s important imho, to use crosshead bits from a high quality set made by someone like Bosch, rather than screwdrivers and to test the fit of several different bits before attempting to loosen screws that you know are going to be tight.
If you can find a bit that fits perfectly with no slop or play, you have an enormously better chance of getting them out easily and intact.