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P011A on the 2016 Mazda Mazda3

The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.

Nobody has written a description of this code yet.

Bulletins for this model year that name P011A
07-007-19-36382019-11-21. Service bulletin. Some customers may complain about poor heater performance even after the engine reaches normal operating temperature. This may be caused by a plugged heater core. For 2014-2016 Mazda6 and 2013-2016 (US spec) / 2017 (Mexico spec) CX-5, the CHECK ENGINE light may turn on with DTC P011A:00 (ECT sensor No.1/No.2 performance problem) stored at the same time. NOTE: Refer to TSB 01-015/15 if the customer is using a block heater at temperatures below freezing. To solve this concern, two mass production changes have been implemented. a) The concentration of the coolant has been increased so that the amount of the contained anti-rust additive is higher. b) The composition of the coolant has been changed (the ratio of the anti-rust additive has increased).
07-007-17-33842017-10-21. Service bulletin. Some customers may complain about poor heater performance even after the engine reaches normal operating temperature. This may be caused by a clogged heater unit. For Mazda6 and CX-5, the check engine light may illuminate with the DTC P011A:00 stored at the same time. P011A:00 ECT sensor No.1/No.2 performance problem. NOTE: Refer to TSB 01-015/15 if the customer is using a block heater at temperatures below freezing.
01-015-15-30642017-05-17. Service bulletin. SOME VEHICLES USING AN AUXILIARY HEATER (BLOCK HEATER) MAY EXPERIENCE THE CHECK ENGINE LIGHT ON WITH DTC P0116:00 OR P011A WHEN STARTING IN COLD WEATHER BELOW 32 °F (0 °C). • P0116:00: ECT SENSOR NO.1 CIRCUIT RANGE/PERFORMANCE PROBLEM • P011A:00: ECT SENSOR NO.1/NO.2 PERFORMANCE PROBLEM. THIS IS CAUSED BY ERROR DETECTION LOGIC OF THE PCM. TO CORRECT THE PROBLEM, THE CONTROL LOGIC OF THE PCM HAS BEEN CHANGED.

3 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.