Suunto is recalling some of its D9 and D6 diving computers, after identifying a software bug that may cause the instruments to track dive time incorrectly.

The bug means that dive time passes 25% slower than actual time, and tissue loadings are recorded at 25% less than actual loadings. There is reckoned to be a 0.6% chance of the problem occurring on a dive.

No incidents have been recorded to date as a result of the bug, says Suunto, but it is asking owners of computers with specified serial numbers (62102582 and below for the D9, 62103693 and below for the D6) to return them straight away. Suunto will provide a free software update that it says will eliminate the problem.

In the meantime, Suunto strongly recommends that affected computers should not be used for diving, unless a back-up unit is available.

If you own one of the affected D9 or D6 computers, take it to your nearest local authorised Suunto retailer for the software update as soon as possible. As a complimentary service, Suunto will at the same time replace your battery and perform a pressure test free of charge. For more information, visit www.suunto.com.