OBD Guide

P03B8

Cylinder 4 Pressure Too Low

P03B8 is an OBD-II diagnostic trouble code meaning: Cylinder 4 Pressure Too Low. Common causes: piston ring wear, malfunction of cylinder valves. Estimated repair cost: $56–222.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–222 (est.)

Symptoms

  • Unstable engine operation
  • Power Loss
  • Increased fuel consumption
  • Misfires
  • Engine vibration

Causes

  • Piston ring wear
  • Malfunction of cylinder valves
  • Problems with the fuel injector
  • Damage to the cylinder head gasket
  • Worn or damaged cylinder

How to Fix

  1. Check compression in cylinder 4
  2. Inspect valves and piston rings
  3. Check the operation of the fuel injector
  4. Inspect the cylinder head gasket for damage
  5. If necessary, replace worn parts

Related codes

Error P03B8 by Vehicle Brand

FAQ

What does the P03B8 code mean?

P03B8 is an OBD-II diagnostic trouble code that indicates: Cylinder 4 Pressure Too Low

What causes a P03B8 error code?

The most common causes of P03B8 include: Piston ring wear; Malfunction of cylinder valves; Problems with the fuel injector; Damage to the cylinder head gasket.

How do I fix a P03B8 diagnostic trouble code?

To fix P03B8: Check compression in cylinder 4. Inspect valves and piston rings. Check the operation of the fuel injector. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P03B8?

Limited driving only, diagnose soon

How much does it cost to fix P03B8?

The estimated repair cost for P03B8 is $56–222. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat