DTC P2123 [13B-MSP]

DIAGNOSTIC PROCEDURE

DTC P2123	APP sensor No. 1 circuit high input
DETECTION CONDITION	The PCM monitors the input voltage from the APP sensor No. 1 when the engine is running. If the input voltage is more than 4.8 V , the PCM determines that the APP sensor No. 1 circuit input voltage is high. Diagnostic support note This is a continuous monitor (CCM.) The MIL illuminates if the PCM detects the above malfunction condition in the first drive cycle. FREEZE FRAME DATA is available. The DTC is stored in the PCM memory.
POSSIBLE CAUSE	Connector or terminal malfunction Short to power supply in wiring harness between APP sensor terminal F and PCM terminal 1AO APP sensor No. 1 malfunction Open circuit in wiring harness between APP sensor terminal E and PCM terminal 1 AS PCM malfunction
Courtesy of MAZDA MOTORS CORP.

DTC REFERENCE CHART

STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	INSPECT APP SENSOR CONNECTOR FOR POOR CONNECTION Turn the ignition switch off. Disconnect the APP sensor connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion.) Is there any malfunction?	Yes	Repair or replace the terminal, then go to Step 8.
3		No	Go to the next step.
4	INSPECT APP SENSOR NO. 1 SIGNAL CIRCUIT FOR SHORT TO POWER SUPPLY Turn the ignition switch to the ON position (engine off.) Measure the voltage between APP sensor terminal F (wiring harness-side) and body ground. Is the voltage B+ ?	Yes	Repair or replace the wiring harness for a possible short to power supply, then go to Step 8.
4		No	Go to the next step.
5	INSPECT APP SENSOR NO. 1 Inspect the APP sensor No. 1. (See ACCELERATOR PEDAL POSITION (APP) SENSOR INSPECTION [13B-MSP] .) Is there any malfunction?	Yes	Replace the APP sensor, then go to Step 8. (See ACCELERATOR PEDAL REMOVAL/INSTALLATION [13B-MSP] .)
5		No	Go to the next step.
6	INSPECT PCM CONNECTOR FOR POOR CONNECTION Turn the ignition switch off. Disconnect the PCM connector. Inspect for poor connection (such as damaged/pulled-out pins, corrosion.) Is there any malfunction?	Yes	Repair or replace the terminal, then go to Step 8.
6		No	Go to the next step.
7	INSPECT APP SENSOR NO. 1 GROUND CIRCUIT FOR OPEN CIRCUIT Turn the ignition switch off. Inspect for continuity between APP sensor terminal E (wiring harness-side) and PCM terminal 1AS (wiring harness-side.) Is there continuity?	Yes	Go to the next step.
7		No	Repair or replace the wiring harness for a possible open circuit, then go to the next step.
8	VERIFY TROUBLESHOOTING OF DTC P2123 COMPLETED Make sure to reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. Start the engine. Is the same DTC present?	Yes	Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION [13B-MSP] .)
8		No	Go to the next step.
9	VERIFY AFTER REPAIR PROCEDURE Perform the "AFTER REPAIR PROCEDURE". (See AFTER REPAIR PROCEDURE [13B-MSP] .) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [13B-MSP] .)
9		No	DTC troubleshooting completed.