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Home >> Mazda >> 1997 >> MX-5 Miata STO, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Emission Systems & Sub-Systems >> Exhaust Gas RECIRCULATION (EGR) System >> EGR Boost Sensor
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EGR Boost Sensor

  1. If testing barometric pressure signal side of sensor, go to step 5). If testing EGR boost signal side of EGR boost sensor, connect Engine Signal Monitor (49 9200 162A) to ECM, using proper overlay and adapter cables. Turn ignition on. Disconnect vacuum hose from EGR boost sensor. Sensor is located in right rear of engine compartment.
  2. Measure voltage at ECM terminal 3N while applying vacuum to EGR boost sensor. Voltage should decrease as vacuum is increased. See EGR BOOST SENSOR SPECIFICATIONS  table. If voltage is as specified, sensor is functioning properly. If voltage is not as specified, go to next step.
  3. Turn ignition off. Check continuity of circuits between EGR boost sensor wiring harness connector and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If continuity exists in all circuits, go to next step. If continuity does not exist in one or more circuits, repair open circuit in wiring harness as necessary.
  4. Turn ignition on. Measure voltage at Black/Blue wire at EGR boost sensor wiring harness connector. Voltage should be less than one volt. Measure voltage at Light Green/White wire at EGR boost sensor wiring harness connector. Voltage should be 4.5-5.5 volts. If voltage is as specified, replace EGR boost sensor. If voltage is not as specified, locate and repair short circuit in wiring harness. See appropriate wiring diagram in WIRING DIAGRAMS article.
  5. To test barometric pressure signal side of sensor, connect Engine Signal Monitor (49 9200 162A) to ECM, using proper overlay and adapter cables. Turn ignition on. Disconnect vacuum hose from EGR boost sensor. Sensor is located in right rear of engine compartment.
  6. Measure voltage at ECM terminal 3H while applying pressure then vacuum to EGR boost sensor. See EGR BOOST SENSOR SPECIFICATIONS  table. If voltage is as specified, sensor is functioning properly. If voltage is not as specified, go to next step.
  7. Turn ignition off. Check continuity of circuits between EGR boost sensor wiring harness connector and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If continuity exists in all circuits, go to next step. If continuity does not exist in one or more circuits, repair open circuit in wiring harness as necessary.
  8. Turn ignition on. Measure voltage at Black/Blue wire at EGR boost sensor wiring harness connector. Voltage should be less than one volt. Measure voltage at Light Green/White wire at EGR boost sensor wiring harness connector. Voltage should be 4.5-5.5 volts. If voltage is as specified, replace EGR boost sensor. If voltage is not as specified, locate and repair short circuit in wiring harness. See appropriate wiring diagram in WIRING DIAGRAMS article.
EGR BOOST SENSOR SPECIFICATIONS

With In. Hg Applied Volts
EGR Boost Signal Side Of Sensor
2.0 3.4-4.2
10.8 2.2-2.7
12.8 1.9-2.4
19.7 1.0-1.2
Barometric Pressure Signal Side Of Sensor
(1) 3.8-4.6
Zero 3.6-4.4
16.1 1.7-2.0
(1) With .79 psi (5.5 kPa) of pressure applied.
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