P0141 — O2 Sensor Heater Circuit (Bank 1 Sensor 2)
P0141 is the heater circuit fault for the downstream (catalyst monitor) O2 sensor on Bank 1. The diagnostic is identical to P0135 — fuse, resistance, and power/ground tests before sensor replacement. Exhaust heat can damage the wiring near the downstream sensor.
Fault Overview
Failed downstream O2 heater element, wiring open or short, blown fuse, and ground issues are the primary causes. Downstream sensors fail heaters less often than upstream, but the diagnostic is identical.
Engine & Platform Coverage
Symptoms
- •P0141
- •downstream O2 heater
- •Bank 1 Sensor 2 heater
- •catalyst monitor sensor heater
Possible Causes
- 1.Failed downstream O2 heater element
- 2.Wiring open or short
- 3.Blown fuse
- 4.Ground issues
- 5.Exhaust heat damage to wiring
Wiring & Circuit Notes
Downstream O2 sensor heater circuit. Check for exhaust heat damage to wiring and connector.
DVOM Specs & Sensor Tests
Heater resistance (typically 2–10 Ω cold). Current draw when heater is commanded on. Voltage supply and ground.
Diagnostic Flow — FSM Sequence
AI Diesel Tech enforces this evidence-gate sequence. Each gate must pass before advancing.
4 steps locked behind Technician Mode- 1Step 1 — Check Fuse: Check the O2 heater fuse for the downstream sensor circuit.
- 2Step 2 — Measure Heater Resistance: Measure heater resistance at the downstream sensor (typically 2–10 Ω cold).
- 3Step 3 — Verify Power and Ground at the Connector: Verify power and ground at the connector with the heater commanded on.
- 4Step 4 — Inspect Wiring for Heat Damage: Inspect wiring for heat damage near the exhaust and sensor.
- 5Step 5 — Replace Sensor if Heater Is Failed: Replace the downstream O2 sensor if the heater element is confirmed failed and the circuit is good.
Unlock the full evidence-gated diagnostic sequence, DVOM test steps, and repair procedures in Technician Mode.
Full Diagnostic Access
Verification steps, preventative measures, severity guidance, and legacy comparison are available in Technician Mode.
Typical Repair Costs
Replace downstream O2 sensor $50–280; repair wiring $50–200.
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Summary
Use the AI Diesel Tech diagnostic engine to run this code through a structured, evidence-gated sequence and get a confirmed root cause before any parts are replaced.