Keyless go issue S213

[Skydog65]

Good morning all,
My keyless go on 68 S213 has suddenly decided to fail to lock or unlock doors and requires fob to be in its holder. Occasionally no key found. have generally done so anyway but odd occasion not with no problems. Passenger seat, pocket, in a bag,
It's both fobs, changed batteries in both. Car battery Bosch agm 80amp fitted beginning September.
It had been left unlocked for about 2 hrs prior to this on Tuesday evening. Done a 5 short journeys since. There and back again. 6 miles being furthest single trip and in daytime. Other 3 trips of 3 miles at night.
Not physically checked car battery but app says its charged. Don't have a scanner.
Any thoughts gratefully received.

 

[Uky]

Possible causes:

1. RFI (transmitter nearby) operating near or on 433 MHz using high(er) power. Could be anything
ISM like baby alarm, wireless weather station, remotes used for switching or monitoring
household appliances. Also switch-mode power supplies used in garden ligthing or eg.solar cell installations can affect systems
and services operating at 433 MHz. (Where I live, such installations has degraded
cell phone performance at 900 MHz.

2. Bad coin cells from the store shelf?.

The instrument cluster should display a warning message about keyfob batteries going bad
as each keyfob transmitted message includes coin cell voltage. After a number of consecutive
Bad-battery messages, the system should display a warning message like "Replace keyfob battery" but sometimes it does not due to battery
having recuperated between keyfob activations. Often caused by temperature variations.

3. Is TPMS working? (System is warning by location, a trigger is sent from each wheel house hidden antenna at 125kHz. TPMS sensor reports back using 433 MHz.)
Error messages could be due to bad 433 MHz receiver in the car.

4. Keyfob placed next to or inside a metal object? Inside the car, there are several small 125kHz antennas placed in various locations
that are used when the car tries to find out if the keyfob is inside the car (OK for start) or outside (OK for unlock or lock).

 

[Skydog65]

Possible causes:

1. RFI (transmitter nearby) operating near or on 433 MHz using high(er) power. Could be anything
ISM like baby alarm, wireless weather station, remotes used for switching or monitoring
household appliances. Also switch-mode power supplies used in garden ligthing or eg.solar cell installations can affect systems
and services operating at 433 MHz. (Where I live, such installations has degraded
cell phone performance at 900 MHz.

2. Bad coin cells from the store shelf?.

The instrument cluster should display a warning message about keyfob batteries going bad
as each keyfob transmitted message includes coin cell voltage. After a number of consecutive
Bad-battery messages, the system should display a warning message like "Replace keyfob battery" but sometimes it does not due to battery
having recuperated between keyfob activations. Often caused by temperature variations.

3. Is TPMS working? (System is warning by location, a trigger is sent from each wheel house hidden antenna at 125kHz. TPMS sensor reports back using 433 MHz.)
Error messages could be due to bad 433 MHz receiver in the car.

4. Keyfob placed next to or inside a metal object? Inside the car, there are several small 125kHz antennas placed in various locations
that are used when the car tries to find out if the keyfob is inside the car (OK for start) or outside (OK for unlock or lock).

Good evening,
Thank you for response. Sadly probably none of the above.
Have tried locking in various completely different locations, so very unlikely interference.
Have tried 2 sets of batteries in each fob, 2 nos and 2 brand new,all four test as v good and give red light with button press.
No warning of bad battery on dash.
But definitely have to have fob in holder now, whilst will start it's slow to respond and occasionally " No key detected" but then obviously finds it and starts car.

No reason to suspect TPMS system not working. But ?

Have had faulty/broken SOS antenna replaced about 7 weeks ago. And Ad blue tank replaced month ago ( faulty sensor) and New AGM battery 5th September.
Now booked in for diagnostics but not till 18th. Hopefully may find solution before that.
Thank you for response and suggestions. Much appreciated

 

[Skydog65]

Possible causes:

1. RFI (transmitter nearby) operating near or on 433 MHz using high(er) power. Could be anything
ISM like baby alarm, wireless weather station, remotes used for switching or monitoring
household appliances. Also switch-mode power supplies used in garden ligthing or eg.solar cell installations can affect systems
and services operating at 433 MHz. (Where I live, such installations has degraded
cell phone performance at 900 MHz.

2. Bad coin cells from the store shelf?.

The instrument cluster should display a warning message about keyfob batteries going bad
as each keyfob transmitted message includes coin cell voltage. After a number of consecutive
Bad-battery messages, the system should display a warning message like "Replace keyfob battery" but sometimes it does not due to battery
having recuperated between keyfob activations. Often caused by temperature variations.

3. Is TPMS working? (System is warning by location, a trigger is sent from each wheel house hidden antenna at 125kHz. TPMS sensor reports back using 433 MHz.)
Error messages could be due to bad 433 MHz receiver in the car.

4. Keyfob placed next to or inside a metal object? Inside the car, there are several small 125kHz antennas placed in various locations
that are used when the car tries to find out if the keyfob is inside the car (OK for start) or outside (OK for unlock or lock).

Hi,
Once again thanks for responding and your suggestions.
Thankfully it seemed simpler that.
Won't bore with details or why but ended up checking fuse for Key less go, (319 10A passenger footwell) Removed and then refitted as was ok. Hey presto all now works. locks/unlocks and no more "key not found " so whether its a classic case of switch off/on or bad connection in fuse holder ?
Your attention was much appreciated

cheers