Ambulance trusts have been warned to keep their satellite navigation systems up-to-date after delays in finding addresses were linked to two deaths.
NHS England, which has issued an alert over the matter, said there was also evidence of three other cases of delays attending cardiac arrests - suggesting the patient was not given the best chance of survival.
It said ambulance sat-navs should be kept up-to-date with the latest road layouts, addresses and other information - but this is not being carried out regularly enough, putting patients at risk.
NHS England said the maps used on computer systems in control centres are also not being updated as much as they should.
In a recent 18-month period, 66 cases submitted to the national database of patient safety incident reports related to sat-nav systems, and nine of these related to new locations not yet being uploaded.
NHS England said one case saw an ambulance on the way to a patient who had suffered a cardiac arrest.
The report said the device had not been updated with the road layouts of new estates built in the last few years - and there was a delay of 10 minutes until it arrived on the scene because of this.
It said that central control was then contacted, and it also emerged that their maps were not up-to-date either.
"If the latest maps were programmed into the sat-nav, then the patient may have received Advanced Life Support sooner with earlier defibrillation," the incident report said.
NHS England said: "A Patient Safety Alert has been issued by NHS England to ensure ambulance satellite navigation systems are up-to-date.
"Ambulances are expected to provide a rapid response to life-threatening situations. If delayed, this can impact on patient safety and outcome.
"Ambulance vehicles should have satellite navigation systems that assist crews to identify the location of the emergency. However, reports to the National Reporting and Learning System (NRLS) suggest some ambulance satellite navigation systems may not be up-to-date with new locations, resulting in delays."
There have been many incidents of sat navs causing problems for ambulances in recent years.
In 2006 a London Ambulance Service crew transferring a patient to hospital was sent 200 miles in the wrong direction by a faulty sat nav instead of on a 12 mile journey that should have taken about 30 minutes.
A spokesman for the ambulance service said the crew had not been to Mascalls Park Hospital near Brentwood in Essex before, and only realised they had gone the wrong way when they reached the outskirts of Manchester.
In 2012 an inquest heard that a sat nav delayed an ambulance getting to the home of a nine-year-old boy who died after a severe asthma attack in Bromsgrove, Worcestershire.
An ambulance took 24 minutes to reach the schoolboy and he was pronounced dead shortly after arrival at hospital. It later emerged that the ambulance's sat nav had sent the crew in the wrong direction, but it was found that it would have made no difference to his death.
An NHS England spokeswoman said: "It is vital that these ambulance systems remain up-to-date to prevent unnecessary delays in providing emergency care."