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350matt, Engineer
Category: Mazda
Satisfied Customers: 21713
Experience:  Mechanical Engineer BEng Hons22 years experience
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I was driving down the interstate in my 2015 Mazda 6 and the

Customer Question

I was driving down the interstate in my 2015 Mazda 6 and the engine light came on immediately following i lost power. I managed to pull off to an exit but here I sit. When I try to start it the whole car shakes and then dies
Submitted: 10 months ago.
Category: Mazda
Expert:  350matt replied 10 months ago.


Ok I'd next check the fusebox in the engine bay to ensure that the ECU and fuel pump has 12V to it when the ignition is on

also remove the fuel filler cap and listen for the pump running when you 1st turn the ignition on as it should 'buzz' for a few seconds then switch off

if this is all OK its possible that the engine crank speed sensor is faulty

1st check for spark by removing one of the spark plugs and plug it back into its lead and rest it on the metal of the engine ( DO NOT hold it on place by hand) then have your assistant turn the engine over whilst you watch the plug. It should give a fat blue spark at regular intervals.

If not then check that there's power to the coil pack (at the other end of the plug lead) using a meter. If there’s 12V at the pack but no spark then check the ECU power supply (fuse and relay) and also the connections to the crankshaft speed sensor.

If there is a spark and its still not starting then its likely that the ECU isn't opening the fuel injectors, if the injectors are working you can hear them click - its difficult to hear them with background noise so use a long screwdriver like a stethoscope, placing the handle end in your ear and the metal tip against the body of the injector whilst your assistant turns the engine over.

If you can't hear anything check the ECU power is present by measuring voltage at the fusebox and on its relay socket if OK then check the connections to the crank speed sensor and consider replacing this sensor if the wiring / connections look OK

If the car will start using a squirt of quick/ easi start into the intake then this confirms the problem is lack of fuel

Expert:  350matt replied 10 months ago.


do you still need help?

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Customer: replied 10 months ago.
Thank you for your efforts, but by the time you replied I had two other mechanics within my circle of friends that had suspected either a sensor issue or a fuel issue and both felt not only would it be covered under warranty, but also near impossible to fix it with extreamly limited resources. They recommended I use my Mazda's road side assistance and they had me picked up and at the nearest dealer with a set of keys for my loaner car before your reply reached me. I waited to respond to this until I hear back from the dealer what was wrong and they informed me it was a high pressure fuel pump. They have it on order and once installed they will run further diagnostics checks and let me know when I can exchange their loaner M3 for my M6.
Expert:  350matt replied 10 months ago.