2000 S70 GLT: Code P0102 (MAF low) + ETS light = bad ETM or bad MAF?

[itsmekirby]

Just fixed a bad ECT a few months ago and everything was great until today! Got a code P0102 (MAF sensor low voltage) and the ETS light. Note that I'm just using a generic OBDII, not Vida/Dice. Cruise control not working, idle was hunting at stop lights, and it stalled while I was pulling into my driveway. I was later testing it out and having trouble getting it to start and noticed the tachometer briefly glitch from 0 to 2k rpm while it was trying to turn over, no idea if that could be related or not.

I went ahead and cleaned the MAF, no improvement. Rough idle doesn't immediately improve by disconnecting the MAF. No obvious vacuum leak but haven't done a full smoke test yet.

A lot of this sounds like the dreaded ETM issue. I believe mine is still stock so it was bound to happen sooner or later. Car is at 110k miles with a yellow label ETM and a bosch MAF which I haven't changed since I purchased the car at 60k so that's possibly original as well. I was just confused by getting code P0102 at the same time since I haven't seen many reports of that code coinciding. What diagnostic is needed to differentiate a bad MAF from a bad ETM here?

[RickHaleParker]

ECM-1300 ( P0102 ) Mass air flow (MAF) sensor. Flow too high or too low.


Condition
If Engine control module (ECM) registers that the air mass, which is measured with the mass air flow sensor, is higher than the upper limit value or lower than the lower limit value for longer time than 10 seconds, then diagnostic trouble code ECM-1300, Too high flow or too low flow, is stored. The upper and lower limit value are calculated continuously by the Engine control module (ECM), the values vary with the throttle's position and the engine's rpm.
For upgraded software, released during year 2006 or later, adjustments have been made to the above limit values to cover the errors diagnostic trouble code ECM-130A took care of in earlier software.


Substitute value

• initial boost pressure
  rear heated oxygen sensor (HO2S) control shut off
  misfire diagnosis shut off

For upgraded software, released in 2006 or later, adjustments have been made to substitute values. In the driving cycles where the fault is active, except the above replacement values, then fuel shut-off which also follows the accelerator pedal position will be active and it will not be able to activate cruise control.
Identifying upgraded software ECM/ETM

Fuel cut-off that follows accelerator pedal position.
Engine speed is regulated via fuel cut-off by deactivating the injectors one at a time. Engine speed is determined by gas pedal position sensor position and engine speed is maximized to about 5000 rpm. This reconfiguration can cause the engine to idle very unevenly since the engine control module (ECM) regulates engine speed by cutting of the fuel to the cylinders individually. Do not confuse this reconfiguration (engine behavior) with an actual driveability problem that was present before reconfiguration.

Cruise control off.
Cruise control off during entire operating cycle in which fault was detected.
If the fault is no longer present, the function is available the next time the car is started.

Possible source
Flow too high:

• short-circuit to supply voltage in the signal cable
  open-circuit in the ground lead
  defective sensor

Flow too low:

• air leakage
  contact resistance
  short-circuit to ground in the signal cable
  open-circuit in signal cable
  open-circuit in power supply cable
  defective sensor

Fault symptoms
poor performance

[itsmekirby]

Updating for posterity: replacing the MAF solved this issue. It does not seem to be an ETM issue so far.