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Code 5 - Map Sensor

WARNING: This page is about a different car, the 1989 Honda Accord. However, it is still accessible from the selected car via links, so may be relevant.
  1. Turn ignition off. Remove No. 11 fuse in the under-hood relay box for 10 seconds to reset ECU. Start engine and observe "CHECK ENGINE" light. If light is off, problem is intermittent. Test drive and check again.
  2. If light is on, turn ignition off. Using a "T" fitting, connect a hand-held vacuum pump/gauge into vacuum hose between throttle body and MAP sensor. Start engine. If vacuum is not present, repair as necessary. If vacuum is present and holds, turn ignition off.
  3. Connect 3-wire test harness between MAP sensor and wiring harness. Turn ignition on. Measure voltage between White (pos.) terminal and Green (neg.) terminal. If reading is not about 3 volts, replace MAP sensor. If voltage reading is about 3 volts, substitute a known good ECU. If condition is rectified, replace original ECU.
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