I found this,,,
In the OEM Service Manual error code P1550 is described as O.T.A.S. sensor voltage not plausible.
Possible Cause(s):
Damaged sensor
Damaged circuit wires
Damaged connector or ECU
Open circuit
Service Action:
Check continuity for circuits B-H3, B-H1 and FB-1 ~ FB-5. Refer to Service Manual for locations.
The problem may not be related to the components you replaced, but instead to the wiring, connectors or ECU. At this point you should purchase an OEM service manual in order to locate and test the circuits as outlined in the trouble shooting section.
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