Hyundai Matrix B1805 Engine Trouble Code
What is Hyundai Matrix B1805?
The Hyundai Matrix B1805 check-engine light can indicate issues ranging from minor (loose gas cap) to serious (catalytic converter failure). Professional diagnostic scanning at a dealer or shop will identify the exact cause and required repairs.
B1805 on the Hyundai Matrix
Hyundai Matrix models produced in the mid-cycle refresh years show a statistical uptick in B1805 occurrences linked to the variable valve timing (VVT) actuator. A sludge deposit in the oil galleries feeding the actuator is the leading suspect.
Code Information
| Code Type: | OBD-II Body (B) Trouble Code |
| System: | Body |
| Vehicle: | Hyundai Matrix |
| Brand: | Hyundai |
| Model: | Matrix |
| Code: | B1805 |
B1805 Hyundai Matrix Symptoms
Check Engine Light
Illuminated Hyundai Matrix dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Hyundai Matrix
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Hyundai Matrix
Increased Emissions
Failed emissions test due to B1805
B1805 Code Structure
Understanding what each digit means in the B1805 body trouble code:
| B | 1 | 8 | 0 | 5 |
|---|---|---|---|---|
| Body Code | Fuel And Air Metering | Engine Oil Temperature Sensor Malfunction | Cold Start Injector 1 Malfunction | Crankshaft Position Sensor B Circuit Malfunction |
How to Fix Hyundai Matrix B1805
Diagnostic Steps:
Check if fuel pump primes when key is turned to ON. Measure fuel pressure and verify bright white-blue spark at all plugs. Also verify mechanical timing alignment.
Repair Solution:
Gasoline engines use spark plugs to ignite fuel-air mixture. Proper timing ensures the explosion occurs when the piston is positioned correctly. Incorrect plug wire sequencing causes mistimed ignition, resulting in poor performance.
Technical Notes:
B1805 DTC specifically relates to camshaft timing. When cam timing is over-retarded, the check-engine light illuminates and this code sets. Verify VCT solenoid operation and check for contamination.
Hyundai Matrix B1805 Repair Cost
When B1805 appears on a Hyundai Matrix, a camshaft position sensor swap costs $140–$260 all-in. This is one of the more affordable sensors on this platform. If the wiring harness is also damaged, add $60–$90 for harness repair or section replacement.
B1805 Description
B1805 engine trouble code is related to Crankshaft Position Sensor B Circuit Malfunction.
Main Cause
The primary reason for B1805 OBD-II Engine Trouble Code is: Engine Oil Temperature Sensor Malfunction.
Common B1805 Misdiagnosis on the Hyundai Matrix
A catalytic converter is often condemned on the Hyundai Matrix when B1805 appears and an efficiency code is present. Before replacement, verify that the upstream oxygen sensor is not slow-responding — a lazy O2 sensor mimics catalytic inefficiency perfectly.
DIY Repair Guide: B1805 on Hyundai Matrix
Replacing the spark plugs on the Hyundai Matrix is rated a difficulty 2/5 for home mechanics. The top-mounted plug access on this engine requires a 3/8" extension and a 14mm spark plug socket. Always torque to the manufacturer's specification to avoid cracking the cylinder head.
Preventing B1805 on the Hyundai Matrix
Inspecting the Hyundai Matrix wiring harness conduit grommets annually — especially the floor pan grommet — costs nothing and takes 10 minutes. Catching moisture ingress early eliminates the most common electrical trigger for B1805 on this model.
Frequently Asked Questions — Hyundai Matrix B1805
A: Yes. Any stored fault code — including B1805 — will cause an automatic failure in most OBD-II based emissions tests. The code must be resolved and the vehicle must complete a full OBD drive cycle with no new codes before the test.