Check if the media size used is supported. Media narrower than A4 (210 mm / 8.27 in.) and shorter than 250 mm / 9.84 in. cannot be duplexed.
Check if the paper bail is supported. Media over 28-lb. bond (105 GSM) is not supported for duplex printing.
Make sure that the printer is on a flat, level surface. An uneven surface results in 231.x5 jams, other jams and issues picking paper, or bad image skew.
Make sure that nothing is interfering with the sheet when it is being pulled back into the printer after the first side is printed.
Note: Do not touch the sheet while it is reversing.
If there are multiple pages in the duplex path, try emptying the output bin to ensure that another page is not getting pulled back into the printer when duplexing. Comply with this step if there is narrow media in the output bin.
Check media loading to make sure that the side guides are set properly to the media size and are snug against the paper loaded in the tray.
Check that the S1 flag on the Tray 1 rotates freely and returns to its original position as shown below.
If the media is longer than Letter/A4 (such as legal, folio, or oficio);Try running Letter/A4 from the same source tray or try running the longer media from Tray 1.
- Does duplexing Letter/A4 media function properly?
- Is the longer media being run from an option tray?