CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2017 Mazda Mazda6 has slight jerk and speedometer drop

Driving manual transmission, 60 mph no change in speed for several miles. Slight jerk, speedometer dropped about 10 mph, came back up to 60 and dash lights dimmed a little, did not flash. Also noticed my music (MP3 via USB) had a minor “skip” or almost sounded like a “scratch” if it was a vinyl record. Does not feel like there is any real loss to speed when this happens. Also noticed that the gear guage that tells you what gear you are in and what gear to find next in dash has gone black.

Sounds like there could be a problem.

I suspect a failing powertrain control module. There may be other problems as well. In any event, if your Mazda has fewer than 60k it’s possible you’re covered under the powertrain warranty so start with your Mazda dealer.

Thank you for your response. We bought it used in December and have 45000
miles on it. I also bought an extended warranty. Could it possibly be
electrical/wiring harness. I saw another post where rodents had eaten the
wire coverings, (soy-based?) and there were issues.

I hope for your sake that the warranty is from the vehicle manufacturer. The aftermarket warranties from other sources usually contain so many weasel clauses that collecting on a claim is either impossible or will result in only a partial reimbursement.

If that turns out to be the case, I don’t think that any warranty will cover the repairs.

1 Like

Before you do anything else, check the battery cables. Make sure they’re tightly clamped to the posts and are clean, without a bunch of green or white gunk on them. What you describe can happen if a battery cable loses connection with its terminal.

4 Likes

It’s certainly possible. Bear in mind, I’m not a mechanic, just a fellow motorist who tries to make helpful suggestions. If it’s the PCM you have 15,000 miles of warranty left, if it’s wiring you’re probably out of luck. In any case, take it to a Mazda dealer.