Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[JamesV6CDX]

I was getting code 38 - low voltage for lambda one

I swapped the sensors around and cleared the codes, but the code 38 has come back, so it's not the sensors.

Please can someone help  

I suspect a wiring problem? But electickery and me don't mix too well  

[cem_devecioglu]

how abouts fuel consumption compared to before (healthy state) ?

[JamesV6CDX]

how abouts fuel consumption compared to before (healthy state) ?

The same.... economy is actually reasonable...

[cem_devecioglu]

if lambda sensors become fubar , fuel economy definitely changes :-/

mine did..

James I estimate you have tech II similiar devices cant you monitor their voltages ?

[JamesV6CDX]

if lambda sensors become fubar , fuel economy definitely changes :-/

mine did..

James I estimate you have tech II similiar devices cant you monitor their voltages ?

I am able to read and reset codes, but not look at live data
I have asked TB if we can plug his Tech2 in relatively soon - hopefully the live data may give an idication as to what's up.

[cem_devecioglu]

if lambda sensors become fubar , fuel economy definitely changes :-/

mine did..

James I estimate you have tech II similiar devices cant you monitor their voltages ?

I am able to read and reset codes, but not look at live data
I have asked TB if we can plug his Tech2 in relatively soon - hopefully the live data may give an idication as to what's up.

yep..

[Marks DTM Calib]

Why narrow it to wiring when it could be an engine fault!

Anyway, here is the checking procedure:

Conditions required to raise code:

1.) Coolant temperature is greater than 70 °C (158 °F);
2.) Condition 1.) fulfilled for 3 min;
3.) Engine load signal is greater than 1.7 ms;
4.) After conditions 1.) to 3.) are fulfilled, waiting period of 5.1 s elapsed;
5.) Following trouble code not recognised: 73, 74;

Replacement value:

450 mV (oxygen sensor closed loop control is disabled)

Concerned terminals - 28 and 10

So what the above is saying is that the code is raised only once the engine is hot (so it not on the warm up cycle) and the engine is loaded (and not initial idling!) plus, the MAF sensor is not nackered.

My next steps would be to measure at the O2 sensor end to check the heater voltage is there......and work from this

But, dont rule out an injector fault or similar!

[JamesV6CDX]

Thanks mark

Interesting what you say - as it does only log the code once it's up to temp

[JamesV6CDX]

You say terminals 28 and 10 - do you mean on the ECU plug?

[Marks DTM Calib]

You say terminals 28 and 10 - do you mean on the ECU plug?

Yes

You should be able to measure the presence of 12V across two terminals at the lambda also which are the heater feeds, the third connection is the lambda signal and the 0V is via the exhaust

[JamesV6CDX]

Do you happen to know what colours the heater feeds are on the sensor, Mark?

[Marks DTM Calib]

Do you happen to know what colours the heater feeds are on the sensor, Mark?

From memory

0V - Brown (pin A?) and 12V - Red/Black (Pin B?)

[JamesV6CDX]

Does it matter if I measure for 12v across the heater when the car is cold or hot?

[philhoward]

I'd guess not - heater voltage should be applied from startup.

Correct me if i'm wrong - but itsn't the heater only used DURING warmup?  After its warm, there should be no need for the heater, so surely its the actual Lambda voltage you're looking for?

[Kevin Wood]

IIRC, the heater is driven from the fuel pump relay so it should be powered whenever the engine is running.

I'd check the wiring to that Lambda carefully, as I recall it being a bit loose when we were under there. Maybe it has caught on the exhaust.

If the heater supply checks out OK have a look at the voltages at the ECU input for the 2 sensors - or view the live data and see what's happening.

Kevin