Infiniti I35 B1566 Engine Trouble Code
What is Infiniti I35 B1566?
The Infiniti I35 B1566 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.
B1566 on the Infiniti I35
The turbocharged variants of the Infiniti I35 are more likely to generate B1566 as boost-related over-fuelling trips the ECU threshold. Inspect the intercooler hoses for micro-cracks that allow unmetered air into the intake stream.
Code Information
| Code Type: | OBD-II Body (B) Trouble Code |
| System: | Body |
| Vehicle: | Infiniti I35 |
| Brand: | Infiniti |
| Model: | I35 |
| Code: | B1566 |
B1566 Infiniti I35 Symptoms
Check Engine Light
Illuminated Infiniti I35 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Infiniti I35
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Infiniti I35
Increased Emissions
Failed emissions test due to B1566
B1566 Code Structure
Understanding what each digit means in the B1566 body trouble code:
| B | 1 | 5 | 6 | 6 |
|---|---|---|---|---|
| Body Code | Fuel And Air Metering | Fuel Composition Sensor Circuit Malfunction | Cylinder 4 Contribution/Balance Fault | Ignition Coil A Primary/Secondary Circuit Malfunction |
How to Fix Infiniti I35 B1566
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:
Brake switch circuit concerns may involve open or shorted BPP circuits, damaged switches, or misadjustment. Verify stoplight function and follow proper self-test procedures per service manual.
Technical Notes:
B1566 DTC indicating a sensor fault does not always mean the sensor itself is bad. The issue may stem from the systems being monitored or even the sensor wiring. Proper diagnosis is essential.
Infiniti I35 B1566 Repair Cost
Addressing B1566 on your Infiniti I35 typically involves: dealer diagnostic fee $95–$150, oxygen sensor replacement $180–$320 (parts + labour), or catalytic converter replacement $1,800–$2,400 if damage has progressed. Independent specialist garages often charge 20–30% less than franchised dealers for identical work.
B1566 Description
B1566 engine trouble code is related to Ignition Coil A Primary/Secondary Circuit Malfunction.
Main Cause
The primary reason for B1566 OBD-II Engine Trouble Code is: Fuel Composition Sensor Circuit Malfunction.
Common B1566 Misdiagnosis on the Infiniti I35
Fuel injector replacement is over-prescribed on the Infiniti I35 for B1566 when the actual fault is a weak fuel pump. Low fuel rail pressure causes lean misfire that looks identical to injector failure in static scan data without a live fuel pressure test.
DIY Repair Guide: B1566 on Infiniti I35
Clearing B1566 on your Infiniti I35 with a basic OBD-II reader ($20–$40) is straightforward: plug the reader into the diagnostic port under the dashboard, read the stored code, and clear it. If it returns within one drive cycle, the underlying fault is still present and requires attention.
Preventing B1566 on the Infiniti I35
Spark plug replacement at the manufacturer's interval — typically 30,000–60,000 miles depending on plug type — is the single most cost-effective preventive maintenance item for avoiding B1566 on the Infiniti I35.
Frequently Asked Questions — Infiniti I35 B1566
A: Yes. Some fault conditions, particularly those involving EVAP system leaks or marginal sensor readings, store codes without producing noticeable drivability symptoms. These are called memory faults and still need to be addressed because they will eventually cause performance issues.