O/T Lambda sensors

[Meldrew]

I have had two lambda sensors fail on the family Volvo V70 sprogtank recently. The second time, a wheel sensor on the ABS/traction control sensor failed pretty much simultaneously.

 

This is not an immediate problem as it's still under warranty, but seems a worry given that it comes out of cover in September.

 

What could be causing repeated lambda sensor failures - and is it likely to mess up a wheel speed sensor at the same time? I wondered if there was some sort of electrical problem.

 

Local Volvo agent are "looking into it" which I'm sure means that they sill slap some new sensors in and give the car back without a moment's further thought.

 

Any ideas, gurus?

[JAG]

I can't think of many common circuits to the Lambda and ABS sensors. Also the Lambda sensor is an 'active' sensor (has power feed to it) whilst the ABS sensors are USUALLY 'passive' (no power feed). So not a lot of common ground - hence little chance of common cause failure.

 

All this suggests that perhaps Volvo' sensor suppliers were having quality problems around the time your car was manufactured.

 

 

Justin

 

A closed mouth gathers no foot.

[Meldrew]

Thanks, Justin - that's what I thought. The only thing that occurred to me was that they are both monitored by the dashboard computer and I wondered if something may have occurred (eg a short of voltage surge ) that might have knackered them both?

 

Most odd.

[JAG]

The ABS system normally has it's own ECU which is integrated with the motor and solenoid valves in a large aluminium block situated under the bonnet, near the booster/master cylinder.

 

There will be a seperate ECU for the engine and other sub-systems. There may be some interconnectivity but that probably only goes as far as the ABS ECU telling the engine when the brakes are being applied and when the ABS is cycling.

 

Hhmmmm I guess it MAY be possible although unlikely.

 

Sorry.

 

 

Justin

 

A closed mouth gathers no foot.

[Mick Day]

"A lambda sensor's normal life span is 30,000 to 50,000 miles. But the sensor may fail prematurely if it becomes clogged with carbon, or is contaminated by lead from leaded petrol or silicone from an antifreeze leak or from silicone sealer."

 

See here for info on lambda sensors: http://www.picotech.com/auto/lambda_sensor.html

 

 

[Meldrew]

Thanks for your input on this.

 

Apparently it's a different Lambda sensor that failed this time - it appears to have three of them 😳 - and since the car does lots of short journeys, it ,may not be surprising that they're getting gunged up.

 

Doesn't explain the wheel sensor, but I guess it's just how it is.

 

Thanks.