Diagnostic procedure

DTC P0121 - DIAGNOSTIC PROCEDURE

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 FREEZE FRAME DATA on repair order, then go to the next step.
2	VERIFY RELATED PENDING CODE OR STORED DTC Turn key to ON (Engine off). Retrieve pending or stored DTC using the WDS or equivalent. Is DTC P0101 also retrieved?	Yes	Go to DTC P0101 troubleshooting procedure.
2		No	Go to the next step.
3	VERIFY RELATED REPAIR INFORMATION AVAILABILITY Check for related Service Bulletins and/or online 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, then go to the next step.
3		No	Go to the next step.
4	VERIFY CURRENT INPUT SIGNAL STATUS - IS CONCERN INTERMITTENT OR CONSTANT Start the engine. Access ECT, TP and MAF PIDs using the WDS or equivalent. Warm up the engine until ECT PID is above 70 °C {158°F}. Drive the vehicle. Read TP PID while MAF PID is above 88.3 g/seconds {11.7 lb/minutes}. Is TP PID reading above 12.5%?	Yes	Go to Step 7.
4		No	Go to the next step.
5	VERIFY TP PID Start engine. Access TP, MAF and RPM PIDs using the WDS or equivalent. Read TP PID while MAF PID is below 5.3g/s {0.7 lb/min} and RPM PID is above 500 RPM. Is TP PID reading above 50%?	Yes	Go to Step 12.
5		No	Go to the next step.
6	VERIFY CURRENT INPUT SIGNAL STATUS - IS CONCERN INTERMITTENT OR CONSTANT Drive the vehicle and read MAF PID. Does MAF PID change in compliance with driving condition?	Yes	Intermittent concern exists. Go to INTERMITTENT CONCERNS troubleshooting procedure.
6		No	Check Mass airflow sensor and related circuits and terminals. (See MASS AIRFLOW (MAF)/INTAKE AIR TEMPERATURE (IAT) SENSOR INSPECTION .) Repair or replace as necessary, then go to Step 16.
7	CHECK TP SENSOR TERMINALS FOR ELECTRICAL CORROSION Turn the ignition switch off. Disconnect TP sensor connector Check for electrical corrosion on male and female TP sensor terminals. Is any electrical corrosion found?	Yes	Repair or replace suspected terminal or TP sensor, then go to Step 11.
7		No	Go to the next step.
8	VERIFY TP SENSOR Does TP sensor resistance smoothly change while gradually opening throttle valve?	Yes	Go to the next step.
8		No	Replace TP sensor, then go to Step 11.
9	CHECK PCM TERMINALS FOR ELECTRICAL CORROSION Disconnect PCM connector. Check for electrical corrosion on PCM male and female terminals. Is any electrical corrosion found?	Yes	Repair terminal, then go to Step 11.
9		No	Go to the next step.
10	CHECK CONSTANT VOLTAGE SUPPLY AND TP SIGNAL CIRCUITS FOR VOLTAGE DROP Connect breakout box with PCM connected. Turn key to ON (Engine off). Check voltage between following terminals: TP sensor connector terminal C (harness-side) and breakout box terminal 33 TP sensor connector terminal B (harness-side) and breakout box terminal 40 Is voltage approx. 0 V?	Yes	Remove breakout box, then go to the next step.
10		No	Check for rust or corrosion on PCM terminals 40 and 33 (harness-side). Repair or replace suspected terminal. Remove breakout box, then go to the next step.
11	VERIFY TROUBLESHOOTING OF DTC P0121 COMPLETED Make sure to reconnect all disconnected connectors. Start the engine. Clear the DTC from the PCM memory using the WDS or equivalent. Access ECT, TP and MAF PIDs using the WDS or equivalent. Warm up the engine until ECT PID is reading above 70 °C {158°F}. Drive the vehicle and read TP and MAF PIDs. Verify PIDs reading are within specifications MAF PID: above 88.3 g/s {11.7 lb/min} TP PID: above 12.5% more than 5 seconds Is pending code of same DTC present?	Yes	Replace PCM, then go to Step 17.
11		No	Go to Step 17.
12	CHECK TP SENSOR TERMINALS FOR ELECTRICAL CORROSION Turn the ignition switch off. Disconnect TP sensor connector. Check for electrical corrosion on male and female TP sensor terminals. Is any electrical corrosion found?	Yes	Repair or replace suspected terminal or TP sensor, then go to Step 16.
12		No	Go to the next step.
13	CHECK GROUND CIRCUIT FOR VOLTAGE DROP Check resistance between TP sensor terminal A (harness-side) and body ground. Is resistance approx. 0 ohm?	Yes	Go to the next step.
13		No	Repair or replace for rust or corrosion on PCM terminal 20 (harness-side) Repair or replace suspected terminal. Go to Step 16.
14	VERIFY TP SENSOR Does resistance smoothly change while gradually opening throttle valve?	Yes	Go to the next step.
14		No	Replace TP sensor, then go to Step 16.
15	CHECK PCM TERMINALS FOR ELECTRICAL CORROSION Disconnect PCM connector. Check for electrical corrosion on PCM and PCM connector male and female terminals. Is any electrical corrosion found?	Yes	Repair terminal, then go to the next step.
15		No	Go to the next step.
16	VERIFY TROUBLESHOOTING OF DTC P0121 COMPLETED Make sure to reconnect all disconnected connectors. Start engine. Clear the DTC from the PCM memory using the WDS or equivalent. Access RPM, TP and MAF PIDs using the WDS or equivalent. Verify TP PID is reading below 50% while MAF PID is below 8.25 g/s {1.09 lb/min} and RPM PID is above 500 RPM. Is pending code of same DTC present?	Yes	Replace PCM, then go to the next step.
16		No	Go to the next step.
17	VERIFY AFTER REPAIR PROCEDURE Perform the "After Repair Procedure". (See AFTER REPAIR PROCEDURE .) Are any DTCs present?	Yes	Go to the applicable DTC inspection. (See DTC TABLE .)
17		No	Troubleshooting completed.