Lambda vs MAP sensor

[Jme34]

Alright folks. Had an 'engine management light' pop up the other day, and then disappear again a few days later. Checked it with a clip, and while the engine is running, the pre cat lambda is running at 19mV (not the few hundred mV it should be), but with the ignition on/engine off it reads at 400 odd mV, which is exactly as it should be. Planning on changing the upstream lambda, but could it be the MAP sensor at fault instead?? Considering the lambda reads fine with the ignition on.

Apologies for the essay and many thanks [emoji5][emoji5]

 

[Rone]

Lambda sensors go bad often. MAP sensors do not go bad as often. So based on statistics, I would go for the lambda. But are there any other symptoms? A failing MAP sensor would probably cause pretty noticeable running problems. A failing lambda sensor might cause the emission readings and the fuel consumption to be a bit off.

 

[Jme34]

Lambda sensors go bad often. MAP sensors do not go bad as often. So based on statistics, I would go for the lambda. But are there any other symptoms? A failing MAP sensor would probably cause pretty noticeable running problems. A failing lambda sensor might cause the emission readings and the fuel consumption to be a bit off.

Bang on there, emissions are poor at the moment and fuel consumption is up as its running rich (I think). Don't think there's any other symptoms to speak of... idle doesn't, but never has, sounded particularly steady, think that's normal on these cars. Thanks for the help, I'll get a proper Bosch lambda and see what happens when I switch it out! Fingers crossed! Tah again!