Yeah, sounds like wiring. This is the one adjacent to the thermostat, right?
Did you follow the troubleshooting guide for Code 6. Nice two-page list. Verifies voltages and resistance at both the sensor end and (first) the ECU.
1988 Coupe Manual Pages 11-28 & 11-29
Oops!, Just noticed your have a 2.0 TURBO. JDM version for sure.
Don't think it'd be much different, but could be.
Did you follow the troubleshooting guide for Code 6. Nice two-page list. Verifies voltages and resistance at both the sensor end and (first) the ECU.
1988 Coupe Manual Pages 11-28 & 11-29
Oops!, Just noticed your have a 2.0 TURBO. JDM version for sure.
Don't think it'd be much different, but could be.