PGM FI Code 1 O2 Sensor Diagnosis (HSN 0587-06)

SERVICE INFORMATION

Here's some additional information we think you'll find invaluable when troubleshooting a suspected oxygen (O2) sensor problem (PGM-FI Problem Code 1) on any fuel-injected Honda.

* After resetting the ECU, it's quicker and easier to check the fuel

pressure before performing the electrical checks. If the fuel

pressure is above 36 PSI with the vacuum hose connected to the fuel

pressure regulator, the regulator is the source of the problem code

and must be replaced.

* Hold the engine at 1500 RPM for 15 minutes, instead of 1500-2000

RPM for 10 minutes. Watch for the problem code to reappear on the

PGM-FI ECU's LED. (The PGM-FI warning light may not come on.) If

the LED does not light, the problem is probably an intermittent

poor connection. Make sure that all the related connectors are

properly seated, reset the ECU, and give the car back to the

customer. If the problem reoccurs, inquire about the customer's

driving habits, further diagnosis may be required.

* When you're performing the electrical checks on the oxygen sensor

and its circuits (with a digital multi-tester), you should obtain

at least 0.6V at wide open throttle and below 0.4V when the

throttle is quickly released (not at idle). When the engine is

idling, the voltage will fluctuate between 0.1 and 0.9.

* If you get to the last step of troubleshooting afid substitute a

known-good ECU, confirm that all the connections are good by

performing the "15-minute test" again.