OBD Guide
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P0042

HO2S Heater Control Circuit Bank 1 Sensor 3

P0042 is an OBD-II diagnostic trouble code meaning: HO2S Heater Control Circuit Bank 1 Sensor 3. Common causes: break or short circuit in the heater wiring, faulty oxygen sensor heating element. Estimated repair cost: $6–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$6–89 (est.)

Symptoms

  • Check Engine Light Is On
  • Increased fuel consumption
  • Unstable engine operation at idle
  • Reduced engine power
  • Increased toxicity of exhaust gases
  • Difficulty starting the engine when cold

Causes

  • Break or short circuit in the heater wiring
  • Faulty oxygen sensor heating element
  • Oxidation or corrosion of sensor connectors
  • Sensor heater relay malfunction
  • Damage to the heater circuit fuse
  • Engine control unit malfunction
  • Poor contact in the sensor connector

How to Fix

  1. Read error codes with a scanner and write down the freeze frame parameters
  2. Visually inspect the oxygen sensor and its wiring for damage.
  3. Check the integrity of the heater circuit fuses
  4. Measure the resistance of the sensor heating element (should be 2-14 Ohms)
  5. Check the supply voltage at the sensor connector (should be 12V)
  6. Check the integrity of the wiring from the ECU to the sensor
  7. Clean oxidized sensor connector contacts
  8. If necessary, replace the oxygen sensor
  9. Clear error codes and take a test drive
  10. Recheck for errors

Related codes

P0041P0043P0044P0135P0141P0161

Error P0042 by Vehicle Brand

AcuraAudiBAICBMWBYDBuickCadillacChanganCheryChevroletChryslerCitroenDodgeDongfengExeedFAWFordForthingFotonGACGMGMCGeelyGreat WallHavalHondaHongqiHyundaiInfinitiJACJaecooJaguarJeepJetourKaiyiKiaLadaLexusLi AutoLifanLincolnLivanMazdaMercedes-BenzMercuryMitsubishiNIONissanOldsmobileOmodaOpelPeugeotPlymouthPontiacRenaultSWMSaturnSkodaSkywellSubaruSuzukiTankToyotaVolkswagenVolvoVoyahXPengZeekrZotye

FAQ

What does the P0042 code mean?

P0042 is an OBD-II diagnostic trouble code that indicates: HO2S Heater Control Circuit Bank 1 Sensor 3

What causes a P0042 error code?

The most common causes of P0042 include: Break or short circuit in the heater wiring; Faulty oxygen sensor heating element; Oxidation or corrosion of sensor connectors; Sensor heater relay malfunction.

How do I fix a P0042 diagnostic trouble code?

To fix P0042: Read error codes with a scanner and write down the freeze frame parameters. Visually inspect the oxygen sensor and its wiring for damage.. Check the integrity of the heater circuit fuses. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P0042?

Limited driving only, diagnose soon

How much does it cost to fix P0042?

The estimated repair cost for P0042 is $6–89. Actual cost depends on your vehicle, location, and labor rates.

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