Infiniti G37 B1566 Engine Trouble Code
What is Infiniti G37 B1566?
Infiniti G37 B1566 code can indicate a faulty oxygen sensor, which may eventually damage the catalytic converter (repair cost: $2,000–$2,200). Professional diagnosis costs around $200–$210. Oxygen sensors are often straightforward to replace — check your owner's manual for location and instructions. This issue should be addressed promptly to prevent further damage.
B1566 on the Infiniti G37
Infiniti G37 models produced in the mid-cycle refresh years show a statistical uptick in B1566 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: | Infiniti G37 |
| Brand: | Infiniti |
| Model: | G37 |
| Code: | B1566 |
B1566 Infiniti G37 Symptoms
Check Engine Light
Illuminated Infiniti G37 dashboard warning
Engine Stalling
Engine stops unexpectedly or misfires
Performance Issues
Reduced power or acceleration on the Infiniti G37
Starting Problems
Difficulty starting the engine
Poor Fuel Economy
Increased fuel consumption on the Infiniti G37
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 G37 B1566
Diagnostic Steps:
Regarding B1566, carefully inspect the wire harness near the intake manifold bracket, best accessed from below near the oil filter. Look for chafing, pinching, or damaged insulation.
Repair Solution:
Firing order is engineered to minimise vibration. Altering firing order results in mistimed ignition and poor engine operation. Consult vehicle-specific repair manual for correct firing order.
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 G37 B1566 Repair Cost
Torque converter clutch solenoid replacement on the Infiniti G37 — relevant for owners who tow regularly — costs $280–$480. A full transmission fluid change ($120–$160) at the same service is recommended because contaminated fluid accelerates solenoid wear.
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 G37
The Infiniti G37 knock sensor shares its harness with the coolant temperature sensor. A corroded shared ground causes both sensors to report out-of-range values simultaneously, leading to misdiagnosis of B1566 as a knock sensor fault when the root cause is the shared ground splice.
DIY Repair Guide: B1566 on Infiniti G37
The fuel pressure test on the Infiniti G37 requires a Schrader-valve type fuel pressure gauge ($25–$40) connected to the fuel rail test port. With the ignition ON (engine off), pressure should hold above 30 PSI for two minutes. A rapid drop confirms a leaking injector or failing regulator as the root cause of B1566.
Preventing B1566 on the Infiniti G37
Scheduled inspection of the Infiniti G37 air filter every 15,000 miles can prevent the intake restriction that leads to B1566. A blocked filter forces the engine to run rich, stressing the catalytic converter and ultimately storing fault codes.
Frequently Asked Questions — Infiniti G37 B1566
A: Temporarily clearing B1566 can help determine whether it is intermittent or persistent, but it does not fix the underlying fault. The code will return if the problem is still present. Do not clear codes just before an emissions test without a proper drive cycle.