Circuit Description

Code is set when either of the following conditions is present:

• Sensor heater current draw exceeds 2 amps, or voltage drop of circuit exceeds 5 volts.
• Sensor heater current draw is .25 amps or less.

Possible causes are:

• Heated oxygen sensor open or short circuit.
• Heated oxygen sensor heater.
• ECM malfunction.

Fig 1: Code P0135, P0141 & P0155 Flow Chart - Heated O2 Sensor Heater Circuit Malfunction

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