P0169 low

O2 Sensor Heater Circuit Low Voltage (Bank 2, Sensor 3)

The P0169 code means the vehicle's onboard diagnostic system has detected: O2 Sensor Heater Circuit Low Voltage (Bank 2, Sensor 3). This is a low severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
easy
Estimated cost
$80 - $300 (parts and labor)
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Common Symptoms

  • Check Engine Light illuminated
  • Extended O2 sensor warm-up time
  • Higher cold-start emissions
  • No noticeable driveability issues

Probable Causes (Ranked by Likelihood)

  • Open O2 sensor heater element Very High
  • Blown heater circuit fuse High
  • Broken wire in heater supply circuit Moderate
  • PCM heater driver not providing ground Low

Step-by-Step Diagnostic Procedure

  1. Check O2 sensor heater fuse first.

  2. Measure heater resistance at sensor connector. Infinite ohms confirms open heater element.

  3. Verify battery voltage is present at the heater supply wire with key on.

  4. Check PCM ground control signal with a test light on the ground wire while commanding heater on.

Frequently Asked Questions

What does heater circuit low voltage mean?

Low voltage means insufficient current is flowing through the heater, typically caused by an open heater element, blown fuse, or broken wire.

Should I check the fuse first?

Yes, always check the O2 sensor heater fuse first. It is the simplest and cheapest fix.

How do I know which fuse is for the O2 sensor heater?

Check your owner's manual or the fuse box cover diagram. Look for labels like O2 HTR or EFI Heater. The fuse is typically 15-20 amps.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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