Hi all.  The EMS light came on a couple of months ago and after visits to the Skoda dealer, the fault was diagnosed as needing a new Lambda sensor.

 

This was fitted on Tuesday.

 

First time I take a journey myself in the car (other than the 2 miles home from the dealer) and the EMS light is back on again.  Has anyone had any similar problems relating to Lambda sensors and why a change has not fixed the fault.  I know it could be a new fault, but that's a bit unlikely given the light is back within 10 miles.

 

Thanks.

If it was fitted with Skoda dealer drive it back to them and ask if they can help you.

>Has anyone had any similar problems relating to Lambda sensors and why a change has not fixed the fault.

 

The fault may be lambda sensor related e.g. wiring or connections, but not actually the lambda sensor itself.

 

Alternately the actuator (Electronic Control Unit) which relies on the sensor for information, may not control the mixture as designed.  So it records a fault via the malfunction indicator lamp (MIL), yellow engine light on the dashboard.

 

In other words the lambda sensor is OK, but the overall fuel injection control circuit isn't working correctly.  The sensor is meant to measure the amount of oxygen in the exhaust - too much oxygen and the engine is running weak, too little oxygen and it's too rich.  For a cold start/acceleration etc. under load it needs a rich mixture and cruising/part throttle it needs a leaner mixture.

 

If the ECU and/or wiring is at fault, just changing a serviceable lambda sensor won't cure the problem.  Once changed, the sensor should be tested and preferably undergo a 'cold start' prior to release to the customer.

 

Take it back and report to Skoda UK (not the Dealer) if you're not happy.  You could do the test yourself and take it back immediately if it's not to your satisfaction.

 

Cheers...The Citigo Kid, Marown - IoM.

Have a look at the wiring where the loom goes behind the battery. On my old Citigo, the wiring had chafed against the back of the stuff mounted behind the battery and thrown up a O2 sensor code. Dealer spotted it straight away (Prestons in Writtle) and had it fixed in minutes.