Hard Or Intermittent Trouble Code E44: Notes

NOTE: Following procedure is designed to account for intermittent codes. If no malfunction is uncovered using this procedure, it will indicate that DFI system is okay at this time.

When oxygen sensor is cold (below 200°C), output voltage will be around 0.5 volts and ECM will keep system in open loop mode of operation. When oxygen sensor is warm (above 200°C), output voltage will swing between 0 and 1.0 volt. When ECM sees that oxygen sensor is not at cold voltage of 0.5 volt, it will send system into closed loop operation. In closed loop operation, ECM will meter fuel into engine based on oxygen sensor readings.

Trouble code indicates that oxygen sensor voltage reading is below 0.5 volt and will not swing above. If voltage remains in this low range, ECM will set code "E44" and return system to open loop operation. Possible causes of this condition are: Oxygen sensor not functioning properly, defective wiring, terminals, etc., improper fuel delivery, or ECM not processing signal properly.

NOTE: The following step numbers refer to the numbers in the accompanying flow chart(s).

To check operation of oxygen sensor circuit, turn ignition on and display engine data parameter P.0.7. If reading is less than .37 volts with sensor disconnected, check circuit No. 412 for short to ground or short to circuit No. 413. If circuit No. 412 is okay, check for faulty ECM connector or faulty ECM.
If voltage is greater than .37 volts, then jumper oxygen sensor harness pin to ground (ECM side) and note reading. If reading is greater than .05 volt, then ECM is not able to recognize that fault was artificially created. Check circuit Nos. 412 and 413 for an open. If no defect is found, check for faulty ECM connector or faulty ECM.
If voltage reading is less than .05 volt, then ECM is functioning properly, and harness is okay. Reconnect oxygen sensor and clear code "E44" before exiting diagnostics. (Code must be cleared prior to checking air management system because air management is disabled whenever hard code "E44" is present). The diagnosis should now center on determining why fuel mixture is lean. A fuel delivery system which is not functioning properly will cause a lean fuel mixture. This malfunction can be caused by fuel pressure less than 9 PSI at the injectors, by defective injectors, etc. See CHART A11 "FUEL SYSTEM DIAGNOSIS". A loss of EGR will cause a lean fuel mixture. See PERFORMANCE CHART NO. 3. If the AIR management system were to send air to exhaust ports at all times, this oxygen would give a lean indication at oxygen sensor. See PERFORMANCE CHART NO. 2. If CHART A4 "OXYGEN SENSOR TEST" indicates that sensor is okay, check all connectors, terminals, etc. for intermittent code.