Heated Oxygen Sensor (HO2S) (front) circuit no activity detected code may be set by
- Low fuel level.
- HO2S sensor (front) malfunction.
- Open or short circuit between PCM connector C254 terminal No. 2 and HO2S sensor terminal No. 1.
- Intake air system, fuel system ignition system malfunction.
- Check HO2S (front) and PCM connections. Repair as needed. Go to next step.
- Check PCM pin voltage at connector C254 terminal No. 2. See «PIN VOLTAGE CHARTS»(ref-25101) article. If voltage is okay, go to step 6). If voltage is out of specification go to next step.
- Disconnect HO2S (front) connector. Check continuity between PCM connector C254 terminal No. 2 and HO2S sensor connector terminal No. 1. If continuity exists, go to next step. If continuity does not exist, repair wiring.
- On 1.8L go to next step. On 1.6L, check continuity between PCM connector C254 terminal No. 7 and HO2S sensor connector terminalNo. 2. If continuity exists, go to next step. If continuity does not exist, repair wiring.
- Ensure fuel injectors, fuel pressure regulator, MAF sensor, ECT sensor, ignition and intake are working properly. Repair as needed.
- Clear code. Recheck codes. If code returns, replace PCM. If code does not return, problem is intermittent.