Infiniti Q45 B1566 Engine Trouble Code
What is Infiniti Q45 B1566?
Infiniti Q45 B1566 indicates potential catalytic converter failure. If completely failed, your vehicle may not run properly and fuel economy will suffer significantly. Average replacement cost is $2,000–$2,140. This repair requires professional service and should not be delayed.
B1566 on the Infiniti Q45
The Infiniti Q45 uses a dual-port fuel injection architecture that is sensitive to ethanol content variations. When E10 fuel is substituted with E5, or vice versa, the fuel trim corrections can cross the DTC threshold and store B1566 in the ECU.
Code Information
| Code Type: | OBD-II Body (B) Trouble Code |
| System: | Body |
| Vehicle: | Infiniti Q45 |
| Brand: | Infiniti |
| Model: | Q45 |
| Code: | B1566 |
B1566 Infiniti Q45 Symptoms
Check Engine Light
Illuminated Infiniti Q45 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Infiniti Q45
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Infiniti Q45
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 Q45 B1566
Diagnostic Steps:
The catalytic converter has oxygen sensors before and after it. When warm and in closed-loop mode, the upstream O2 sensor reading should fluctuate, while downstream should remain steady.
Repair Solution:
Verify all electrical connections are clean and tight. Check for damaged wiring, especially in high-heat or high-vibration areas. Use manufacturer wiring diagrams for accurate diagnosis.
Technical Notes:
B1566 on electronically controlled automatic transmissions relates to shift solenoid operation. The solenoid actuates hydraulic circuits controlling clutches or bands for gear changes.
Infiniti Q45 B1566 Repair Cost
Crankshaft reluctor ring inspection and replacement on the Infiniti Q45 is a major service item costing $600–$1,100. Given the labour required to access the component, it is advisable to replace the rear crankshaft seal and crankshaft position sensor simultaneously while the area is open.
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 Q45
The Infiniti Q45 is frequently taken to workshops for a B1566 fault where the technician replaces the throttle position sensor (TPS). In a significant proportion of cases, the root cause is a loose or cracked vacuum hose downstream of the throttle body that should have been found in a basic visual inspection.
DIY Repair Guide: B1566 on Infiniti Q45
Battery terminal cleaning on the Infiniti Q45 is a 5-minute job that resolves a surprising number of B1566 intermittents. Use a wire brush and a bicarbonate of soda solution to clean corrosion, then apply a thin coat of petroleum jelly to the terminals after refitting.
Preventing B1566 on the Infiniti Q45
For Infiniti Q45 owners in high-humidity climates, applying electrical contact cleaner and dielectric grease to the ECU connector pins every two years prevents the corrosion-related signal errors that register as B1566.
Frequently Asked Questions — Infiniti Q45 B1566
A: It depends on the severity. If the check-engine light is steady, it is generally safe to drive to a workshop within the next few days. If the light is flashing, pull over safely as soon as possible — a flashing light indicates an active misfire that can cause expensive catalytic converter damage within minutes.