TPMS 'No sensor detected', despite good readings?

P

Paddy_SP

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Yesterday, I got a dashboard warning that the rear right TPMS sensor had died - the display simply shows '--' highlighted in red. When I hold my Autel 808-TS right next to the valve stems it will communicate with all three of the other wheels, giving the correct PSI, etc. - and yet when I ask it to 'Check MX' (without moving the scanner at all) on any of the wheels, it tells me that no sensor was detected (several attempts got the same result). Since this happens on the wheels that clearly have working sensors, I'm left confused...

Overall, I would like to determine whether the internal battery has died in the faulty sensor, or whether it is a wiring/connector issue at the ECU.

My car is a European model (2015 GTS) and thus has the 433MHz sensors; I therefore set the Autel to the correct model - I can't think of any reason why it might do this. I'd be most grateful to hear from anyone else who has experienced this problem!
 
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No, you not missing anything - it's why I'm so confused - it'll read the PSI, but still tells me that there's no sensor detected!
 
Hang on: You're getting a PSI reading from the sensor it can't detect?

I thought you were using the Autel to interrogate each sensor individually and one of them was not responding.

C
 
Are you using it correctly? For a full sensor check do you need to start with it connected to the OBD and it will then tell you which sensor to check?
 
Here's the scenario:

The car displays 3 wheel pressures, but puts a '--' with a red highlight for the right rear.

In TPMS mode, the Autel will talk to the three functioning sensors and display pressure readings from them, but gets nothing from the 4th wheel.

While still in Autel TPMS mode (basically the same page), if I go into direct MX interrogation it tells me that there is no sensor detected on any of the wheels.
 
Paddy_SP said:
Here's the scenario:

The car displays 3 wheel pressures, but puts a '--' with a red highlight for the right rear.

In TPMS mode, the Autel will talk to the three functioning sensors and display pressure readings from them, but gets nothing from the 4th wheel.

While still in Autel TPMS mode (basically the same page), if I go into direct MX interrogation it tells me that there is no sensor detected on any of the wheels.
Click to expand...

I'd suspect a glitch in the software and you've got a flat battery in the failed sensor. My understanding (again potentially wrong) is that in TPMS mode, it's bypassing everything and just pinging the sensor direct.

C
 
Oneball said:
Do you need to press a button to trigger the sensor?
Click to expand...
Yes - if you click 'Trigger', you get good readings from the three good sensors. Right next to that button is 'Check MX Sensor' (or some similar wording) - but that gets no response from any wheel, which is a shame as it's the one that's meant to tell me the battery status!
 
CatmanV2 said:
I'd suspect a glitch in the software and you've got a flat battery in the failed sensor. My understanding (again potentially wrong) is that in TPMS mode, it's bypassing everything and just pinging the sensor direct.

C
Click to expand...
As far as I'm aware, you're correct - which is why you have to hold the Autel right up next to the valve stem. My wife's Volvo is parked right next to the car though - so to rule out proximity interference, I'll try again in the morning when she's out.
 
It gets stranger - with my wife's Volvo out of the way, I was able to try again without there being any risk of proximity interference from her car's sensors...

I tried the 'Check MX-sensor' method again, but the Autel keeps telling me that no sensor was detected on any of the wheels. And yet, when I used the 'Diagnostics' facility, it gave me a full readout of all four wheels, including the status of all the sensor batteries. All showed to be fine, and none had any issues with 'Low sensor confidence' either. And yet the dash display still shows '--' in a red highlight.

Now, the first thing I did before any of the above was a full error code auto-scan (mostly to deal with the secondary air pressure sensor error that I get every time I drive the car) including a complete error clear. Whether this has 'cured' my fault, I'm not sure. I think I now need to drive the car until it updates the pressure readings to see if the 4th wheel magically re-appears - watch this space!
 
OK - I've test-driven it now, but with no clear resolution. The low tyre pressure warning light on the dash has gone out, but the dash pressure display still shows that wheel as '--' in a red highlight.

If the sensor's battery isn't low and the Autel can communicate with it, then it would suggest that the problem is elsewhere. I think I may pull the TPMS ECU and check the plug for nastiness...
 
I could, but I don't see how that would tell me anything about my car - unless you mean to simply test the MX-sensor function, which is no longer necessary as the diagnostics facility bypassed that!
 
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