Over the years reading stored DTCs from many DI modules, I've found some that have memory failures that indicate a DTC but it's not a real b/c of a bad internal memory bit in the module itself.

It started about 1 year after I got the '94 S500. The DI module suddenly showed the "CKS" sensor as failed. The CKS is a non-electronic device (some wire wrapped around a magnet that measures correctly) so that showed me that a DI module can fail causing the CE ckt to light generating a DTC that is NOT real! Once the CE lamp is on, just try to pass a CA smog test. Real or not, it's counted as real!

After replacing the DI module, a few years later, the module showed a DTC = "Reference Resistor is bad". Well, it's NOT (it's there and measures correctly) but the DI module "thinks" it's bad. The good news is that the REF RES failure does NOT cause the CE lamp to lite b/c it's not an EMISSIONS related failure as was the CKS. This failure has been there for a least 13 years or more.

In your case, I might tend to believe the failure b/c of stalling, hard-starts, etc.

Hope this helps.

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Regards . . . . JimF
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'94 S500 Cpe

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