2000 S70 Base Replaced "Bad" Sensors, No Change

thankswww · Post by **thankswww** » 04 Jan 2014, 23:36

So, do I have a bad ECU (computer)?

My car has been throwing a P0505 code since I bought it. This is the air idle control valve fault code. I replaced the air idle control valve, reset the codes, and the car still throws the code telling me my brand new air idle control valve is bad. I've disconnected the battery and let it sit over the weekend. I've cleared codes using a scanner. The code still comes back within a few start cycles.

My car threw a P0443 (evap purge valve no signal) code. I replaced the purge valve. I cleared the codes several times. Let it sit with battery disconnected, etc. Code comes back again and again and again.

I've also replaced both oxygen sensors, but the ECU keeps throwing codes saying the brand new 02 sensors are bad.

The ECU is throwing a knock sensor (no signal) code as well, but I really, really, really hesitate to pay the dealer to change the sensor, seeing as how every single other sensor that has been replaced has done absolutely nothing to clear the codes or solve the problem of my vehicle getting horrendous gas mileage.

Did I mention that the car runs fine, other than getting Lamborghini gas mileage? The plugs look fine, and the fuel pressure is right at where it should be at idle.

The plugs on the sensors all look good and there is no corrosion.

So I guess what I'm asking is what do all of these sensors have in common? Is it possible that each and every one of these sensors is somehow disconnected from the ECU? Where would the likely break in connection be?

My car's ECU is getting no input from the following sensors:

Front 02 Sensor (new)
Rear O2 Sensor (new)
Air Idle Control Valve (new)
Emissions EVAP Purge Valve (new)
Camshaft Position Sensor (not replaced)
Knock Sensor (not replaced)

The only thing I can find in common is that all of these sensors are located and have wiring that trails around the right side of the engine.

Post by **kcodyjr** » 04 Jan 2014, 23:42

Certainly does smell like a wiring harness issue. Look carefully.

Post by **burnout8488** » 05 Jan 2014, 08:01

"Idle Air Control", Not air idle control. Might help with searches, might not.

Does the '00 S70 even have that? I was under the impression that idle was controlled by the ETM in 99 and 00 model S70s, turbo and non turbo.

Do you have a picture of the valve you replaced?

You are in Korea though, so perhaps that market had a different engine management.

Post by **precopster** » 05 Jan 2014, 12:35

That idle air control threw me as well. Does it have electronic throttle body fitted?

thankswww · Post by **thankswww** » 05 Jan 2014, 20:49

Indeed, I have a picture of the valve that I replaced:

Yes, the car has an electric throttle body.

I think the problem must be with the wiring somewhere. The only question is where should I start? At the ECU, or in the engine bay...

Either something is disconnected, or several wires are cut somewhere. Perhaps chewed by a rodent, or something. I feel that the car is getting horrible mileage because it is probably dumping extra fuel into the combustion chamber due to the lack of any signal whatsoever from the knock sensor/emissions system/O2 sensors. I may be wrong. I am actually shocked that the car runs so well, considering that it is not getting any signal from any of these sensors.