[ViperGRM]

Hi folks,

I hope someone can help me with this fault. I've been trying to get it fixed by a few local mechanics but I'm getting very different diagnoses.

Mechanic Workshop 1) Told me it was because my oil level was too high and recommended an oil change and engine flush. Within minutes of getting the car back, the same fault code came back on. £155 wasted it seems, £45 of which was to run the diagnostics and clear the fault code, which I could have cleared myself. By the way, this was the third time I've used this garage and the third time they were unable to fix fault, so I'm done with them.
Mechanic Workshop 2) Advised that it was likely due to carbon build-up and it may also be related to an intermittent fault i've been having (error code P0401). They said I would need to strip the engine down to clean it and I needed a special tool to remove some of the parts. They then told me they don't have this part and recommended another garage. I called this other garage and they couldn't even look at it for weeks, plus they were ridiculously expensive (almost £100 per hour).

I've read from other folk on forums that the vacuum pump failure is quiite common on these cars, so I don't know if mechanic 2 was assuming worst case scenario. It is really hard for me to say. I do hace a pressure test kit which I bought on a whim one time, but have never actually used it. Are these easy to test to confirm a fault?

I should also mention that I paid to have the engine carbon cleaned using a hydrogen machine. The place that did it got rave reviews, so thought I would give it a try. It didn't clear the fault either. The car is driving fine too.

I'd really appreciate any recommendations. Thank you!

 

[Michelle66]

Hi folks,

I hope someone can help me with this fault. I've been trying to get it fixed by a few local mechanics but I'm getting very different diagnoses.

Mechanic Workshop 1) Told me it was because my oil level was too high and recommended an oil change and engine flush. Within minutes of getting the car back, the same fault code came back on. £155 wasted it seems, £45 of which was to run the diagnostics and clear the fault code, which I could have cleared myself. By the way, this was the third time I've used this garage and the third time they were unable to fix fault, so I'm done with them.
Mechanic Workshop 2) Advised that it was likely due to carbon build-up and it may also be related to an intermittent fault i've been having (error code P0401). They said I would need to strip the engine down to clean it and I needed a special tool to remove some of the parts. They then told me they don't have this part and recommended another garage. I called this other garage and they couldn't even look at it for weeks, plus they were ridiculously expensive (almost £100 per hour).

I've read from other folk on forums that the vacuum pump failure is quiite common on these cars, so I don't know if mechanic 2 was assuming worst case scenario. It is really hard for me to say. I do hace a pressure test kit which I bought on a whim one time, but have never actually used it. Are these easy to test to confirm a fault?

I should also mention that I paid to have the engine carbon cleaned using a hydrogen machine. The place that did it got rave reviews, so thought I would give it a try. It didn't clear the fault either. The car is driving fine too.

I'd really appreciate any recommendations. Thank you!

Did you manage to get your car sorted, I have a 2014 Mazda 6 exactly the same problem was looking for advice

 

[ViperGRM]

Did you manage to get your car sorted, I have a 2014 Mazda 6 exactly the same problem was looking for advice

Hi @Michelle66 unfortunately I still haven't been able to get it fixed yet. I've been to several mechanics, none of which have been able to confirm the fault. I bought a used, working replacement pump and was hoping for my mechanic to fit it. He loooked at the location and said that it would be very awkward to remove. He also said it wasn't the vacuum pump at fault because if it was, the brakes wouldn't work. My brakes do work fine, but if I press the brake continously, it isn't long before it stops working. That is because there is no air in the vacuum and it takes a while to regenerate. This is apparently normal. Mine seemed to stop working fairly quickly but it could just be in my head. He thinks it might be a sensor issue but I'm not sure.

It's been a long story and I have not got to the bottom of it yet. I have been posting updates about it in this post: EGR Valve Cleaning on 2014 Sport Nav 2.2D

I will try post a further update about it later today. I think at this stage I am considering taking it to the dealer just for the initial diagnostics. They should have better tools than most local garages. I have two fault codes that I can't get rid of. This and P0401 which is EGR related. If you do get yours sorted before me I would appreciate it if you could share the details here. Thank you

 

[Michelle66]

Hi @Michelle66 unfortunately I still haven't been able to get it fixed yet. I've been to several mechanics, none of which have been able to confirm the fault. I bought a used, working replacement pump and was hoping for my mechanic to fit it. He loooked at the location and said that it would be very awkward to remove. He also said it wasn't the vacuum pump at fault because if it was, the brakes wouldn't work. My brakes do work fine, but if I press the brake continously, it isn't long before it stops working. That is because there is no air in the vacuum and it takes a while to regenerate. This is apparently normal. Mine seemed to stop working fairly quickly but it could just be in my head. He thinks it might be a sensor issue but I'm not sure.

It's been a long story and I have not got to the bottom of it yet. I have been posting updates about it in this post: EGR Valve Cleaning on 2014 Sport Nav 2.2D

I will try post a further update about it later today. I think at this stage I am considering taking it to the dealer just for the initial diagnostics. They should have better tools than most local garages. I have two fault codes that I can't get rid of. This and P0401 which is EGR related. If you do get yours sorted before me I would appreciate it if you could share the details here. Thank you

I paid a garage to take a look at the car the map sensor apparently had a crack in it and was very clogged with carbon, he replaced this three times as it kept throwing up different faults including ones with the abs etc third time lucky the car drove lovely for two weeks then ping the engine management light came on with the same fault as yours made the mistake of clearing before taking it to the garage who stated no fault no fix fuel economy today dropped by 10mpg worried sick it’s the dpf but had no warning lights for it had the same fault as yours twice but local garage reckons could be the onboard ecu just throwing faults at me so got to wait for fault to appear then auto electrician it is just worries inbetween times the damage may be lethal or costly any updates will be appreciated

 

[ViperGRM]

I paid a garage to take a look at the car the map sensor apparently had a crack in it and was very clogged with carbon, he replaced this three times as it kept throwing up different faults including ones with the abs etc third time lucky the car drove lovely for two weeks then ping the engine management light came on with the same fault as yours made the mistake of clearing before taking it to the garage who stated no fault no fix fuel economy today dropped by 10mpg worried sick it’s the dpf but had no warning lights for it had the same fault as yours twice but local garage reckons could be the onboard ecu just throwing faults at me so got to wait for fault to appear then auto electrician it is just worries inbetween times the damage may be lethal or costly any updates will be appreciated

It's interesting you mentioned the MAP sensor. Mine was completely blocked up to the point I don't know how it would function. It was just a wall of carbon around the sensor. I cleaned it as best I could and used a needle to poke at the carbon. It was rock hard. I put the MAP sensor back in and it made no difference. In saying that, I guess it's possible it isn't functioning but I'm not sure how to test it.

A few mechanics have said that if my vacuum pump (P258B) was faulty then the brakes wouldn't work. I'm still not entirely convinced it isn't the vacuum pump and I'll explain why.

If I test the brakes on a downward slope by pressing them aggressively for a second, release, brake, release ever few seconds, then they tighten up and don't work very well. This is indicative of no air in the pump, thus the vacuum doesn't work - hence the stiff brake pedal. This is normal for a car to behave in that manner however, mine seemed to stiffen up a lot quicker than normal. I will check by doing the same thing from another car to see how similar it is but at this point I am still not ruling out the vacuum pump.

At this point, I was thinking of just taking it to the main dealer for the initial diagnostics. They should have the best tools available to diagnose the fault. Some garages really do frighten the life out of you by making ridiculous, unfounded statements that your car engine might need replaced etc. I'be been to probably 5 or 6 different mechanics and their opinions have differed dramatically. Here's an overview but bear in mind these visits are more or less all for the P0401 fault I've been having since January.

Garage 1 - Diagnosed fault as EGR valve. Tested and the valve was fine, so they cleaned the EGR valve and it made no difference. Fault return very soon after getting the car back. Cost roughly £120 for EGR clean.
Garage 2 (same garage as Garage 1 but this was the last time I used them) - It's your oil. You need an engine flush and new oil - This cost me £155 for absolutely nothing. It had nothing to do with the oil and the check engine light came on again within minutes of getting the car back.
Garage 3 - Its just carbon build-up. Your engine needs stripped down and cleaned. This could cost a fair bit. After I initially asked them to do it, they called me back a few days later and said they couldn't do it because they needed a tool that costs £800 just to remove part of the engine. To be honest, I think they just didn't fancy taking on the job.
Garage 4 - This was my own choice. I decided to get the engine carbon cleaned by using a hydraulic machine. Lots of people swear by this and think it's great, but this made no difference and the fault was still there. Another £90 but at least the engine is clean(er).
Garage 5 - Had absolutely no idea what was causing the fault. They were honest enough to tell me this and didn't charge me anything.
Garage 6 - Stripped out the EGR valve and EGR cooler and gave it a good clean. Put it all back together but unfortunately the fault is still present. Another £90.

I've done about 10,000 miles since I got the car and the P0401 has been on since I got it. I don't believe I am doing any long term damage because as @Jay at has been saying, it is quite likely to be carbon build-up somewhere, or possibly a sensor fault. It does not affect the performance of the car whatsoever. It'll be great to get to the bottom of this. I'm not giving up just yet. I'll let you know if I make any progress with the vacuum pump. Thanks!

 

[ViperGRM]

Just FYI - @Jay at has pointed out to me that Mazda use software to relearn the MAP sensor to the car when replacing with a new unit. You said yours was replaced 3 times but if it hasn't been correctly relearned then this is a possible issue.

 

[Chris T 2016 2.2]

Hi folks,

I hope someone can help me with this fault. I've been trying to get it fixed by a few local mechanics but I'm getting very different diagnoses.

Mechanic Workshop 1) Told me it was because my oil level was too high and recommended an oil change and engine flush. Within minutes of getting the car back, the same fault code came back on. £155 wasted it seems, £45 of which was to run the diagnostics and clear the fault code, which I could have cleared myself. By the way, this was the third time I've used this garage and the third time they were unable to fix fault, so I'm done with them.
Mechanic Workshop 2) Advised that it was likely due to carbon build-up and it may also be related to an intermittent fault i've been having (error code P0401). They said I would need to strip the engine down to clean it and I needed a special tool to remove some of the parts. They then told me they don't have this part and recommended another garage. I called this other garage and they couldn't even look at it for weeks, plus they were ridiculously expensive (almost £100 per hour).

I've read from other folk on forums that the vacuum pump failure is quiite common on these cars, so I don't know if mechanic 2 was assuming worst case scenario. It is really hard for me to say. I do hace a pressure test kit which I bought on a whim one time, but have never actually used it. Are these easy to test to confirm a fault?

I should also mention that I paid to have the engine carbon cleaned using a hydrogen machine. The place that did it got rave reviews, so thought I would give it a try. It didn't clear the fault either. The car is driving fine too.

I'd really appreciate any recommendations. Thank you!


Mazda should be paying for your issues under the safety recalls

Recall reference
R/2018/236

Recall Type
Car

Recall Date
2018-09-17

Reason for concern
VACUUM PUMP MAY WEAR PREMATURELY.

Reason for recall
The vacuum pump may wear prematurely meaning that in some applications where the brake pedal is pressed quickly whilst at low engine speed � the servo assistance provided by the vacuum system in decreased. This could cause a momentary decrease in braking performance. Braking assistance available to the driver can be reduced

Remedy
Vehicles affected will be fitted with a modified Vacuum pump.

More information:

Recall MAZDA R/2018/236 - Vehicle Recall UK

Recall MAZDA R/2018/236. VACUUM PUMP MAY WEAR PREMATURELY.

www.vehicle-recall.co.uk

Recall reference
R/2018/289

Recall Type
Car

Recall Date
2018-09-17

Reason for concern
INJECTOR MOUNTING NUTS TIGHTENING FORCE MAY BE INSUFFICIENT

Reason for recall
The tightening force of the injector mounting nuts may be insufficient. This could cause combustion gas to leak from the injector and contaminate the engine oil within the cylinder head. This in turn could cause the engine oil strainer to become blocked. This could cause the engine to stall. Engine Pressure Oil Light appears along with the engine malfunction indicator. Possible Engine Stall without Warning

Remedy
Vehicles affected will have the engine checked for contamination and repaired / replaced if necessary. The Fuel injectors will also be re-tightened

More information:

Recall MAZDA R/2018/289 - Vehicle Recall UK

Recall MAZDA R/2018/289. INJECTOR MOUNTING NUTS TIGHTENING FORCE MAY BE INSUFFICIENT

www.vehicle-recall.co.uk

 

[mattyuk]

Interestingly, I have the P258B code and do have a failing vacuum pump. My VIN is within the range stated for the above recall "vacuum pump may wear prematurely", but two separate UK Mazda garages have said that my car is not covered. They couldn't explain why though. If anyone knows better I'd be grateful to understand why that might be the case. I've already bought the replacement pump but if Mazda should be paying for it then I'd prefer them to do it of course.

 

[ViperGRM]

Interestingly, I have the P258B code and do have a failing vacuum pump. My VIN is within the range stated for the above recall "vacuum pump may wear prematurely", but two separate UK Mazda garages have said that my car is not covered. They couldn't explain why though. If anyone knows better I'd be grateful to understand why that might be the case. I've already bought the replacement pump but if Mazda should be paying for it then I'd prefer them to do it of course.

Sorry I've just read this message. Mine didn't appear to be on a recall list either, but Mazda went ahead and did it anyway as goodwill. If your car has an excellent service history with Mazda then maybe they can at least contribute something? It doesn't seem to be too big a job if you know a half decent mechanic if you get nowhere with Mazda.

 

[Gavner]

Hi @Michelle66 unfortunately I still haven't been able to get it fixed yet. I've been to several mechanics, none of which have been able to confirm the fault. I bought a used, working replacement pump and was hoping for my mechanic to fit it. He loooked at the location and said that it would be very awkward to remove. He also said it wasn't the vacuum pump at fault because if it was, the brakes wouldn't work. My brakes do work fine, but if I press the brake continously, it isn't long before it stops working. That is because there is no air in the vacuum and it takes a while to regenerate. This is apparently normal. Mine seemed to stop working fairly quickly but it could just be in my head. He thinks it might be a sensor issue but I'm not sure.

It's been a long story and I have not got to the bottom of it yet. I have been posting updates about it in this post: EGR Valve Cleaning on 2014 Sport Nav 2.2D

I will try post a further update about it later today. I think at this stage I am considering taking it to the dealer just for the initial diagnostics. They should have better tools than most local garages. I have two fault codes that I can't get rid of. This and P0401 which is EGR related. If you do get yours sorted before me I would appreciate it if you could share the details here. Thank you

sounds to me like exhaust gas pressure sensor £60 from Mazda, it a upgraded version. Easy to change 20 min, you must use the new loom they provide with it. Plug it straight in the old loom and new one into new sensor.
also take off boost pipe top front engine, quite a thin pipe under a sensor, it points towards u. Clear the tube pipe was sitting on. I used a blunt needle, blow down other make sure it unblocked. It’s ridiculously thin it easily gets blocked.
Issue solved. 🙂

 

[ViperGRM]

sounds to me like exhaust gas pressure sensor £60 from Mazda, it a upgraded version. Easy to change 20 min, you must use the new loom they provide with it. Plug it straight in the old loom and new one into new sensor.
also take off boost pipe top front engine, quite a thin pipe under a sensor, it points towards u. Clear the tube pipe was sitting on. I used a blunt needle, blow down other make sure it unblocked. It’s ridiculously thin it easily gets blocked.
Issue solved. 🙂

Hi,

Thank you for the reply. Thankfully I didn't need to do any of this. I took it to the dealer and they were brilliant. After an engine decoke at their expense didn't fix the issue, they replaced the EGR cooler. That was over 2 years ago now I think and I've never seen the fault since. They also replaced the vacuum pump at their expense. The car is well out of it's warranty period so I was somewhat blown away by this level of service. Have had a couple of issues with the car since, but no EGR are or vacuum pump issues.

 

[Aboo_UK]

I am about to fit my new vacuum pump this week, I have had P0101 and U0401 for months now, changed MAP sensor, changed MAF sensor twice, and exhaust differential pressure sensor and it has had 2 turbos since I bought it in January 2022. I have been following Kennedy's Garage on YouTube for a while now and the mechanic had this fault, he shows how to diagnose a faulty vacuum pump with a vacuum guage, no mention of poor braking, although when looking for a front bumper from breakers in the UK most were front end damage, maybe coincidence, but this lad is the only one I could find showing exactly these faults and apparently it was just the vacuum pump.