240 L4-2320cc 2.3L SOHC VIN 83 B230FD (1993)
Oxygen Sensor: Testing and Inspection
Function Check
EJ. Diagnostic Trouble Code (DTC) 2-1-2 MFI LH 2.4 And LH 3.1
Heated oxygen sensor (HO2S) signal absent or faulty
If DTC 2-1-2 is logged at the same time as other DTCs, the first code to be presented by the OBD system should be remedied first. The following DTCs
are regarded as secondary faults.
DTC Conditions:
If the signal is absent the control module cannot handle
HO2S control. A DTC is logged if the signal is faulty (over
1.1 V) or absent (0.5 V), 3 minutes after engine temperature has exceeded 80°C (176°F).
Causes of fault:
Breaks, short circuits in the HO2S wiring. Contact resistance in connections. No pre-heating of the HO2S.
Fault symptoms:
High fuel consumption, can cause driving problems.
EJ1
Checking The Signal From The Heated Oxygen Sensor (H025)
-Start and warm up the engine.
Connect a voltmeter between terminal 1 (1-pole connector at the firewall) and GND.
The voltmeter reading should fluctuate between 0.1-0.9 V.
1. If the reading is OK:
Intermittent fault.
-Check the wiring for loose contacts, If no faults are detected, connect the ST.
2. If the reading is constant approx. 0.5 V:
-Check the HO2S pre-heater EJ6.
If the reading is constant approx 0 V:
