P0038 medium Severity

P0038: Heated Oxygen Sensor (HO2S) Heater Control Circuit High (Bank 1, Sensor 2)

Check Engine Light illuminated; possible reduced emissions compliance and minor fuel economy impact

Overview

P0038 indicates a high voltage condition in the heater control circuit of the Bank 1 Sensor 2 heated oxygen sensor, often due to wiring issues, faulty sensor heater element, or PCM driver circuit faults

Common Symptoms

  • Illuminated Check Engine Light (MIL)
  • Possible increased emissions or failed emissions test

Most Common Causes

Faulty Bank 1 Sensor 2 heated oxygen sensor heater element high

Sensor heater element failure can cause excessive current draw or high voltage reading

Damaged or shorted wiring or connector in heater circuit high

Wiring insulation wear, chafed wires near exhaust heat, or pinched harness can trigger high voltage

Open or short to B+ in heater control circuit medium

Circuit issues where battery voltage feeds incorrectly into heater control

Faulty PCM/ECM heater driver circuit low

Rare internal control module failure after wiring and sensor ruled out

Diagnostic Steps

  1. Connect OBD-II scanner and confirm P0038
    Expected: Code P0038 present
    Interpretation: Verify the code is active and note any freeze frame data
  2. Visually inspect Bank 1 Sensor 2 oxygen sensor wiring and connector
    Expected: No chafed, broken, corroded wiring or connectors
    Interpretation: Damaged wiring can cause high voltage and should be repaired
  3. Measure heater circuit resistance with sensor disconnected
    Expected: Resistance in expected range (varies by OEM)
    Interpretation: Out-of-spec resistance indicates sensor heater fault
  4. Measure circuit voltage at connector with ignition on
    Expected: Voltage within normal range per manufacturer
    Interpretation: Consistently high voltage confirms wiring or control circuit issue
  5. If wiring and sensor pass tests, test PCM heater control output
    Expected: PCM driver outputs correct control signal
    Interpretation: Faulty PCM heater driver requires module diagnosis or replacement

Repair Solutions

Replace Bank 1 Sensor 2 heated oxygen sensor medium
Estimated Cost: $80 - $300

Typical cost includes parts and labor; ensure correct sensor application

Repair or replace damaged wiring and connectors medium
Estimated Cost: $20 - $150

Cost varies by extent of wiring harness repair

Replace blown fuse or faulty relay in heater circuit easy
Estimated Cost: $5 - $50

Applicable if circuit protection component has failed

Repair or replace PCM/ECM heater control circuit hard
Estimated Cost: $800 - $1200

Rare case requiring professional module replacement and programming

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Replacing oxygen sensor without checking wiring or connectors first

Frequently Asked Questions

What is the definition of the P0038 engine code?

Technically, the P0038 code represents Heated Oxygen Sensor (HO2S) Heater Control Circuit High (Bank 1, Sensor 2). It usually points to a fault within the Sensors.

Reflecting on severity: How bad is P0038?

The P0038 code is considered medium severity. Check Engine Light illuminated; possible reduced emissions compliance and minor fuel economy impact

What are the symptoms of P0038?

Common symptoms include: Illuminated Check Engine Light (MIL), Possible increased emissions or failed emissions test. You might also notice the Check Engine Light is on.

Common triggers for the P0038 error

This code is frequently triggered by: Faulty Bank 1 Sensor 2 heated oxygen sensor heater element, Damaged or shorted wiring or connector in heater circuit, Open or short to B+ in heater control circuit.

What is the price difference for fixing P0038?

The cost varies significantly based on the root cause. For example, replacing a Replace blown fuse or faulty relay in heater circuit typically costs between $5 and $50, while fixing a Repair or replace PCM/ECM heater control circuit can range from $800 to $1200.

What cars are affected by the P0038 code?

Yes, P0038 is a generic code that applies to all OBD-II compliant vehicles, including Ford, Toyota, Honda, Chevrolet, Nissan, Dodge, BMW, and more.

User Comments (0)

Share your experience or ask a question about this code.

Be the first to share your experience with P0038!