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Home >> Mazda >> 2017 >> CX-5 Grand Select, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 38 (On-Board Diagnostic [Front Body Control Module (FBCM)]) >> DTC U0401-68: Error Signal Received From Pcm >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2016 Mazda CX-5. However, it is still accessible from the selected car via links, so may be relevant.
STEP Inspection Action
1 VERIFY FRONT BODY CONTROL MODULE (FBCM) DTCs AGAIN  Yes Go to the next step.
No Go to Step 6.
2 INSPECT ECT SENSOR  Yes Go to the next step.
No Replace the ECT sensor, then go to Step 5.
(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
3 INSPECT AMBIENT TEMPERATURE SENSOR  Yes Go to the next step.
No Replace the ambient temperature sensor, then go to Step 5.
(See AMBIENT TEMPERATURE SENSOR REMOVAL/INSTALLATION [MANUAL AIR CONDITIONER] .)
(See AMBIENT TEMPERATURE SENSOR REMOVAL/INSTALLATION [FULL-AUTO AIR CONDITIONER] .)
4 PERFORM DTC INSPECTION AND VERIFY IF MALFUNCTIONING PART IS PCM  Yes Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.0, SKYACTIV-G 2.5] .)
No Go to Step 6.
5 VERIFY THAT REPAIRS HAVE BEEN COMPLETED  Yes Replace the front body control module (FBCM), then go to the next step.
(See FRONT BODY CONTROL MODULE (FBCM) REMOVAL/INSTALLATION .)
No Go to the next step.
6 VERIFY IF OTHER DTCs DISPLAYED 
  • Are any other DTCs displayed?
Yes Repair the malfunctioning part according to the applicable DTC troubleshooting.
(See DTC TABLE [FRONT BODY CONTROL MODULE (FBCM)] .)
No DTC troubleshooting completed.