911 C2/C4 DME system fault codes

[tshih]

Hi Tech Masters,

Just found 2 fault codes in the DME system of a 1993 RS America:

1) air flow sensor signal too weak or not present
2) HO2S short to ground not present

Questions: what is HO2S? does this mean there is corrosion likely for this ground to be disrupted?

The 964 air flow sensor is the old mechanical flap Bosch type which was replaced with the more reliable Platinum wire mass flow sensor in the 993 series. Is there a direct bolt on replacement upgrade (along with the chip configured correctly to run that DME system) for this air flow sensor that will make the engine run better?

Appreciate any advice.

Tom

[Britwrench]

These codes on their own do not mean anything. The first thing to do is clear them, drive the car and see what comes up.

You can check the O2 sensor operation and air flow sensor voltage with the Bosch KTS300 tester. Go to "actual values"
on the screen. Air flow sensor voltage should be around
0.19 - 0.23v and 02 sensor voltage around 0.2 - 0.7 and will constantly vary between those two points. (or should do).

Yes, you can buy a hot wire air mass sensor kit.

Taking anything the Bosch hammer says at face value can be very misleading.