Code 25: Barometric Pressure Sensor

NOTE: Barometric (BARO) pressure sensor is built into airflow sensor. For code 25 test purposes, the airflow sensor will be referred to as the BARO pressure sensor. For component terminal identification, see AIRFLOW SENSOR under TERMINAL IDENTIFICATION . For wiring diagrams, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

Manufacturer does not provide component testing procedure without scan tester. Turn ignition switch to ON position. Using scan tester, read sensor pressure. See BARO PRESSURE SENSOR SPECIFICATIONS table. If pressure is not as specified, replace BARO pressure sensor. If pressure is as specified, go to next step.

BARO PRESSURE SENSOR SPECIFICATIONS

Altitude: Ft. (M)	Pressure: In. Hg
0 (0)	29.92
1969 (600)	27.95
3937 (1200)	25.98
5906 (1800)	24.02

Disconnect BARO pressure sensor connector. Using DVOM, check for continuity between chassis ground and BARO pressure sensor connector terminal No. 4 (Non-turbo) or terminal No. 6 (Turbo). If continuity does not exist, repair wiring harness as necessary. If continuity exists, go to next step.
With BARO pressure sensor connector disconnected, turn ignition switch to ON position. Check for voltage between chassis ground and BARO pressure sensor connector terminal No. 3 (Non-turbo) or terminal No. 4 (Turbo). If voltage is not 4.8-5.2 volts, repair wiring harness as necessary. If voltage is as specified, go to next step.
With BARO pressure sensor connector and ECM connector disconnected, ground ECM connector terminal No. 16. Using DVOM, check for continuity between chassis ground and BARO pressure sensor connector terminal No. 3 (Non-turbo) or terminal No. 4 (Turbo). If continuity does not exist, repair wiring harness as necessary. If continuity exists, condition required to set code is not present at this time. Test is complete. Intermittent problem may exist. See TESTS W/O CODES article in the ENGINE PERFORMANCE Section.