2016 Honda Civic: Dithering Throttle Software Fix
by Dan Edmunds, Director of Vehicle Testing on January 24, 2017
You may have already read about the subtle yet annoyingly persistent surge I experienced while cruising on flat highways during my Thanksgiving trip to Oregon. The car has been in high demand since my return, so I've never found time to have it looked over.
I had always suspected this was down to a minor software glitch, and that indeed proved to be the case. An alert reader wrote in to tell us about an official Honda service bulletin #16-028, and a brief internet search turned up the details and a familiar-sounding and remarkably descriptive title: "2016 Civic 1.5L Turbo Surges at Highway Speeds (45-70 mph)."
Yes, it does. Ours, at least.
This is old news, as it turns out, which is fortunate for a good number of other 2016 Civic owners. The bulletin is dated March 17, 2016, and it states that cars built after March 3, 2016, were factory-built with the new software. Civics built before then need an update, but only if they're an EX-T or a Touring sedan with the 1.5-liter turbo engine and the continuously variable transmission (CVT). LX and EX examples with the 2.0-liter engine are not affected whether they have the automatic CVT or not.
Our car checks all the boxes. It's a Touring with the tiny turbo, and the build date printed in the upper right corner of the VIN tag found on the driver's door jamb says it is an early car that was made in October 2015.
The bulletin describes the problem as "incorrect learning values in the TCM [Transmission Control Module] software," and it summarizes the repair in plain terms: "update the TCM."
At 8 a.m. I wheeled into the driveway at Hardin Honda in Anaheim and described the problem to Omar, my service writer. I also played him the video clip I posted here a few weeks ago. He nodded as he wrote it all down and told me they'd need it until noon.
At first this seemed excessive, but he reminded me of the heavy morning commuter traffic on the nearby 57 freeway. They'd have to wait until it died down so they could do the required confirmation drives before and after the reflash, which on its own was a job of no more than 15 minutes.
With no ride home I took advantage of the dealer's free shuttle service, which left seconds after I filled a cup with the free coffee.
A couple hours later Omar called to say they had confirmed the problem and were about to perform the reflash, and he gave me an updated repair timetable that matched his earlier prediction. Less than an hour later he called again to say it was finished, and the same information came in more or less simultaneously via text message at 11:41 a.m. It was all very painless and efficient, and it cost me nothing except time.
I haven't been able to test the result on a road trip similar to the one that highlighted the problem in the first place, but I gave it a good try on the 2-mile freeway cruise back home and detected zero dithering or surging. I think we can put this one to bed.
Dan Edmunds, Director of Vehicle Testing @ 19,301 miles