Signal Too Low. Intermittent Fault

Signal too low. Intermittent fault

EFI-521 Front heated oxygen sensor (HO2S), preheating EFI-522 Rear heated oxygen sensor (HO2S), preheating

Checking cables and terminals




- Check cable between heated oxygen sensor (HO2S) terminal 1 and main relay (2/32) terminal 3 for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
- Check cable between heated oxygen sensor (HO2S) terminal 2 and engine control module (ECM) #A14 (for diagnostic trouble code (DTC) EFI-521)/ #A29 (for diagnostic trouble code (DTC) EFI-522) for an intermittent short-circuit to ground according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults and an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
- Check heated oxygen sensor (HO2S) and engine control module (ECM) connectors for loose connections according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults and contact resistance and oxidation according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.

Caution! Do not apply rust solvent spray or grease to the heated oxygen sensor (HO2S) connector.

Continue - Fault-tracing information
Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).

Do you want to view the information again?

Yes - Attempt New Test

No - FAULT FOUND

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Attempt New Test - Checking cables and terminals

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