Greetings,

Hope this is the right place to ask this. If not, feel free to smack the noob.

I just replaced the engine in my 98 A4 Quatro (2.8L DOHC V6) and the CEL came on after the first test drive. I went to Autozone to have the codes read and it came up with P1158 and P1159 - something to do with the air/fuel mixture.

Does anyone have a more detailed diagnosis of these codes? Is this a common occurance with these vehicles?

I'm guessing part of the problem might be from the used motor sitting around for a while, though I have no idea how long or where it was sitting. I drove it back to work and the light stayed off... so far.

Any help would be greatly appreciated.

Thanks!

Kevin K.

 

strange you should get P1158 as that's a MAP sensor and your engine doesnt have one but the other code makes more sense, P1159 is the MAF sensor bank 1&2 impulse ratio problems could be EGR system / intake leak / wiring to the MAF / MAF sensor 1&2 so you need to check the MAF and here is how,

first the plug is a 3 pin using a multimeter
switch ignition off and disconnect MAF multi plug.
check the resistance between wiring harness pin 2 and ground the resistance should be zero.

next check for battery voltage which is pin 3&2 ignition on plug still disconnected.

checking signal.
ignition off.
do not disconnect MAF multi plug.
switch ignition on start engine and allow to idle.
check voltage between multi plug terminals by back probing the rear of the multi plug the pin numbers are on the outer case so you need to pull the rubber back to expose the wires.

terminals 1&2 ignition on engine off voltage should be 0.3 - 1.1 V.

terminals 1&2 engine idling voltage should be 1.5 V approx.

terminals 1&2 take revs to 4000 rpm voltage should be 3.4 V approx.

if all is correct then chances are it was a voltage spike, if its out of range while engine running then its the MAF sensor, if the first check for ground and live fail then its a wiring fault or the ECM

 

Outstanding! I'll check that when I get home tonight.

I'm a noob to these motors so I want to make sure I have the right plug. It's the one on the tube coming out ot the air box before the flexible hose section, correct?

Thanks a LOT for the reply. You can't ask for more detail than that!

Kevin K.

 

you are correct on the place of the MAF plug

 

I take it that one lower value means the MAF sensor is bad, correct?

Thanks again for your help!!!

Kevin K.

 

my concern is the low voltage at 4000rpm range the rest are withing range, what mods if any have you done to the induction?? fit a new air filter and see if it improves and check for air leaks/cracks in the rubber hose after the MAF sensor

 

I haven't done any mods, I just put the motor in. The only pace I can think of that it might be leaking air would be at the back of the intake where the plastic tube bolts on. I'll check that and see if I have it tightened down.

Thanks again.

Kevin K.

 

If there is a leak after the MAF and the MAF is working fine:

should removing the air filter and checking it again give me a higher voltage?
would installing a high flow aftermarket cone filter help (or are those just bling)?

Kevin K.

 

actually they are as good as the say they are and yes the increased air flow should up the voltage at the 4000rpm range which is where you need it, the K&N panel filter is good

 

also a clean out of the MAF with spray (I use break or throttle body spray) it dries quick don't use anything to touch the sensor in the MAF the spray is strong enough to clean the resistors