Explaining OBD2 Fault Codes P0021-P0030: Causes, Symptoms, and Fixes

by Garage Pro

When an OBD2 scanner pulls up fault codes between P0021 and P0030, they usually indicate issues with camshaft timing or oxygen sensor problems. Understanding these codes is vital for diagnosing engine performance issues, as well as for avoiding costly repairs down the line.

In this guide, we’ll break down each fault code from P0021 to P0030, explain what it means, its symptoms, possible causes, and how you can fix the issue.

P0021: 'A' Camshaft Position Timing Over-Advanced (Bank 2)

What it Means:
Code P0021 relates to the intake camshaft timing being over-advanced on Bank 2. The vehicle's ECU detects that the camshaft has moved beyond its optimal range.

Symptoms:

  • Poor engine performance
  • Rough idling
  • Check Engine Light (CEL)
  • Poor fuel economy

Causes:

  • Faulty Variable Valve Timing (VVT) solenoid
  • Incorrect camshaft timing
  • Low oil pressure
  • Dirty or contaminated engine oil

Fixes:

  • Check and replace the VVT solenoid if needed
  • Ensure the engine oil is clean and at the correct level
  • Inspect timing components for damage or misalignment

P0022: 'A' Camshaft Position Timing Over-Retarded (Bank 2)

What it Means:
P0022 occurs when the intake camshaft timing is over-retarded, meaning it has not advanced enough as the ECU expects.

Symptoms:

  • Poor acceleration
  • Engine stalling
  • Difficulty starting
  • CEL illuminated

Causes:

  • Faulty camshaft position sensor
  • Failed VVT solenoid
  • Dirty or insufficient engine oil
  • Timing chain issues

Fixes:

  • Replace or clean the camshaft position sensor
  • Change the oil and filter
  • Test and replace the VVT solenoid if necessary

P0023: 'B' Camshaft Position Actuator Circuit (Bank 2)

What it Means:
P0023 indicates an issue with the camshaft actuator circuit, specifically the exhaust camshaft on Bank 2.

Symptoms:

  • Rough idling
  • Misfires
  • Engine hesitation
  • Reduced fuel efficiency

Causes:

  • Open or short in the camshaft actuator circuit
  • Faulty camshaft actuator solenoid
  • Wiring issues
  • Low oil levels

Fixes:

  • Repair any wiring problems
  • Test and replace the camshaft actuator solenoid
  • Ensure proper oil maintenance

P0024: 'B' Camshaft Position Timing Over-Advanced (Bank 2)

What it Means:
The exhaust camshaft timing on Bank 2 is more advanced than the ECU’s specified range, triggering a P0024 code.

Symptoms:

  • Harsh engine operation
  • Engine knocking
  • Loss of power
  • CEL illuminated

Causes:

  • Malfunctioning camshaft actuator
  • Incorrect timing chain placement
  • VVT solenoid failure
  • Oil flow problems to the camshaft

Fixes:

  • Replace or service the camshaft actuator
  • Check for and correct timing misalignment
  • Ensure oil is flowing properly to the camshaft

P0025: 'B' Camshaft Position Timing Over-Retarded (Bank 2)

What it Means:
Code P0025 signals that the exhaust camshaft timing is over-retarded, meaning it's not advancing as needed.

Symptoms:

  • Poor engine performance
  • Engine misfires
  • Poor throttle response
  • CEL

Causes:

  • Defective camshaft position sensor
  • VVT solenoid failure
  • Timing chain slack
  • Contaminated engine oil

Fixes:

  • Inspect and replace the camshaft position sensor
  • Change the oil and ensure proper VVT operation
  • Check for timing chain issues

P0026: Intake Valve Control Solenoid Circuit Range/Performance (Bank 1)

What it Means:
P0026 relates to an issue with the intake valve control solenoid on Bank 1, suggesting poor performance or range.

Symptoms:

  • Reduced engine power
  • Rough idling
  • Poor fuel economy
  • CEL illuminated

Causes:

  • Malfunctioning intake valve control solenoid
  • Open or short in the control solenoid circuit
  • Oil sludge affecting valve operation

Fixes:

  • Clean or replace the intake valve control solenoid
  • Address any circuit problems
  • Change engine oil and filter if necessary

P0027: Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 1)

What it Means:
This code refers to a malfunction in the exhaust valve control solenoid circuit on Bank 1.

Symptoms:

  • Engine stalling or hesitation
  • Reduced throttle response
  • Engine misfires
  • CEL illuminated

Causes:

  • Faulty exhaust valve control solenoid
  • Circuit issues (open or short)
  • Poor oil quality

Fixes:

  • Replace the exhaust valve control solenoid
  • Repair or replace faulty wiring
  • Ensure proper oil maintenance

P0028: Intake Valve Control Solenoid Circuit Range/Performance (Bank 2)

What it Means:
P0028 deals with the intake valve control solenoid on Bank 2 and typically indicates a performance problem in the valve's operation.

Symptoms:

  • Rough engine idle
  • Poor acceleration
  • Poor fuel efficiency
  • CEL illuminated

Causes:

  • Defective intake valve control solenoid
  • Dirty or contaminated oil
  • Circuit issues (open or short)

Fixes:

  • Clean or replace the solenoid
  • Fix wiring problems
  • Change oil and filter

P0029: Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 2)

What it Means:
This code indicates an issue with the exhaust valve control solenoid on Bank 2, often related to its electrical circuit or range.

Symptoms:

  • Engine stalling
  • Poor throttle response
  • Misfires
  • CEL illuminated

Causes:

  • Faulty exhaust valve control solenoid
  • Circuit malfunction
  • Dirty engine oil

Fixes:

  • Replace the exhaust valve control solenoid
  • Check for wiring problems

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