Hondata

2002 RSX with PRB and k24/k20 swap. Bought it recently with all this
Related calibration settings: Secondary O2 not enabled, OBDII functions disabled
Throwing P1166 after 10 secs of engine running.
Made some checks according to manual. Fuses, relay seem to be good.
Ended with this voltage reading at Primary O2 sensor plug(harness side) for heater circuit:
- 9.3V between + (WHT) and - (GRN) with engine shut
- 10.7V between + (WHT) and - (GRN) with engine running
- 12.5V between + (WHT) and - (exhaust as ground) with engine shut

Thought it was bad ground at G101, replaced it to valve cover stud as recommended - no luck. Going to clean ground wire at right engine mount, it doesn't look good (but if it can be related?).
Is it general ground problem or something with ECU A1 (heater ground) or its wire?
Datalog shows correct sensors info, e.g TPS works ok from 0 to 100%
Or am I completely wrong and this error is about low voltage at A22 and I should check heater relay output? But sensor side heater positive wire reads 12.5V when exhaust is ground..

P.S Secondary O2 is still plugged (going to unplug tomorrow and recheck). ECU was hanging on harness (not bolted) while testing.

This error has nothing to do with the secondary sensor. More than likely the primary sensor has been damaged and will need to be replaced.

Spunkster wrote: Tue Jun 23, 2020 3:46 pm This error has nothing to do with the secondary sensor. More than likely the primary sensor has been damaged and will need to be replaced.

Thank you for reply!
What about Primary sensor heater voltage that I posted? Why it is so low?
Looks like ground at A1 ECU pin is bad. Is there way to diagnose ECU ground? I guess it is all taken from G101

The best way to test the ECU is to try it in a known working vehicle and see if there are any errors.