Infiniti OBD2 Codes: Full List with Causes and Fixes

BySerge Barrett

When the check engine light comes on in an Infiniti, the OBD2 system has already logged a fault. Infiniti shares its platform and engine family with Nissan, which means many codes are identical across both brands — but some Infiniti-specific codes require a scanner with Nissan/Infiniti manufacturer coverage to read. Below are the most common codes across the Q50, QX60, QX80, FX35, G35, and G37, organised by system with the real cause and what actually fixes the problem.

Engine and Fuel System

  • P0011 — Camshaft position timing over-advanced, Bank 1. Stuck VTC (Variable Timing Control) solenoid or low oil pressure from neglected oil changes. On the VQ35HR and VQ37VHR engines in the G37 and Q50, this code is frequently caused by sludge accumulation in the VTC solenoid oil passages. Clean or replace the solenoid; address oil change intervals.
  • P0014 — Camshaft position timing over-advanced, Bank 1 Exhaust. Same cause as P0011 but on the exhaust cam. On the VQ series, P0011 and P0014 appearing together confirms VTC system fault rather than a sensor issue.
  • P0021 — Camshaft position timing over-advanced, Bank 2. Mirror of P0011 on the opposite bank. When P0011 and P0021 appear together on a V6, the VTC oil control valve on both banks is the likely cause — often an oil maintenance issue.
  • P0087 — Fuel rail pressure too low. Failing fuel pump, clogged filter, or leaking fuel pressure regulator. On the QX80 and QX56 with the VK56VD V8, fuel pump failures are documented from around 120,000 miles. Check fuel pressure with a gauge before replacing the pump module.
  • P0100 — Mass Air Flow sensor circuit fault. Dirty or failed MAF sensor, torn intake boot, or wiring issue. Clean the MAF sensor with dedicated spray first; replace if the code returns.
  • P0101 — MAF sensor range/performance. The sensor is reading but not within expected parameters for current engine load. Common on the VQ35DE after 80,000 miles. Clean the sensor element before replacing.
  • P0117 — Engine coolant temperature sensor voltage low. Failed ECT sensor or corroded connector. On higher-mileage VQ engines, the sensor connector at the thermostat housing is a known corrosion point. Replace sensor and inspect connector.
  • P0128 — Coolant temperature below thermostat regulating temperature. Thermostat stuck open — one of the most common codes across the entire Infiniti/Nissan lineup. Also causes poor heater performance and downstream rich codes. Thermostat replacement resolves it in nearly all cases.
  • P0171 — System too lean, Bank 1. Vacuum leak, dirty MAF sensor, low fuel pressure, or failing upstream O2 sensor. On the VQ35DE in the FX35 and G35, intake manifold gasket leaks are a documented cause at higher mileage. Smoke test for vacuum leaks before replacing sensors.
  • P0172 — System too rich, Bank 1. Failed upstream O2 sensor, stuck-open injector, or ECT sensor fault. When accompanied by P0128, thermostat replacement typically resolves both codes.
  • P0300 — Random/multiple cylinder misfire. Worn spark plugs, failing ignition coils, or timing chain stretch on higher-mileage VQ engines. Replace all spark plugs and coil packs as a set first; check for cylinder-specific codes alongside.
  • P0301–P0306 — Cylinder-specific misfire, cylinders 1–6. Failed coil, spark plug, or injector on that cylinder. Swap the suspect coil to another cylinder — if the misfire code follows it, replace the coil.
  • P0325 — Knock sensor circuit fault, Bank 1. Failed knock sensor, corroded wiring, or sensor mounting bolt not torqued correctly. On the VQ35DE, the knock sensors are mounted in the valley of the block and can be affected by oil sludge. Common DIY repair — sensors are accessible but require intake manifold removal on some variants.
  • P0335 — Crankshaft position sensor circuit fault. No signal from the CKP sensor. Symptoms include no-start or stalling. On the VQ series, the CKP sensor is a known failure item at higher mileage. Replace sensor; inspect wiring harness for damage near the flywheel.
  • P0340 — Camshaft position sensor circuit fault, Bank 1. Failed sensor or timing chain wear affecting signal consistency. On higher-mileage VQ35DE and VQ37VHR engines, timing chain stretch can cause P0340 alongside P0300. Diagnose chain condition before replacing sensors.
  • P0420 — Catalyst efficiency below threshold, Bank 1. Failed upstream O2 sensor at lower mileage; catalytic converter at end of life past 150,000 miles. On the G35 and FX35, confirm O2 sensor function before condemning the converter.
  • P0430 — Catalyst efficiency below threshold, Bank 2. When P0420 and P0430 appear together, both converters have failed — common on high-mileage VQ35DE V6 engines. Address any misfire codes first.
  • P0441 — EVAP system incorrect purge flow. Failed purge solenoid, cracked vacuum hose, or faulty fuel cap. Check the fuel cap seal first.
  • P0448 — EVAP vent control circuit open. The EVAP canister vent solenoid has a fault. On the Q50, a faulty charcoal canister causing this code has been documented — P0448 can return even after vent valve replacement if the canister itself is defective.
  • P0455 — EVAP system large leak. Loose or damaged fuel cap, cracked EVAP hose, or failed vent valve. Start with the fuel cap; smoke test if not the cause.
  • P0507 — Idle RPM too high. Vacuum leak, dirty throttle body, or failed IACV on older models. On the VQ35DE, a dirty throttle body is the primary cause. Clean with throttle body cleaner.

Ignition System

  • P0351–P0356 — Ignition coil primary circuit fault, cylinders 1–6. Failed coil primary winding. On the VQ series, coil failure is a routine higher-mileage repair. Symptoms are a cylinder-specific misfire alongside the coil code. Swap the coil to confirm before replacing.
  • P1272 — Accelerator pedal position sensor circuit (Infiniti-specific). The APP sensor is reading outside expected range. On the Q50 with drive-by-wire throttle, this can trigger a reduced power mode. Requires Infiniti-capable scanner to read this code — generic scanners may not display it. Replace APP sensor assembly.
  • P1564 — ASCD (cruise control) steering wheel switch fault. The cruise control switch inputs are not being received by the ECM. On the Q50 and QX60, this is a known issue often caused by a faulty or worn steering wheel switch. Replacement is required — resetting the code without replacing the switch will not resolve it.

Transmission

  • P0700 — Transmission control system malfunction. General code — TCM has stored its own specific faults. Always appears alongside additional transmission codes. Read all stored codes; P0700 alone does not describe the fault.
  • P0720 — Output shaft speed sensor circuit fault. Erratic speedometer and poor shift scheduling. On the 7-speed JR710E transmission in the Q50 and QX60, this sensor is a known wear item. Replace sensor.
  • P0740 — Torque converter clutch circuit fault. Failed TCC solenoid, contaminated fluid, or worn clutch plate. Highway shudder between 40–60 mph often precedes this code. Change fluid first; replace TCC solenoid if shudder persists.
  • P0744 — Torque converter clutch circuit intermittent. Intermittent TCC solenoid fault — fluid condition is usually the trigger. Fresh transmission fluid often clears this code without further repair on lower-mileage vehicles.
  • P0750 — Shift solenoid A circuit fault. Failed solenoid or contamination in valve body. Solenoid pack replacement is the standard repair on the RE7R01A and 7AT transmissions used in newer Infiniti models.
  • P17F0 — Transmission fluid over temperature (Infiniti/Nissan specific). The transmission has reached or exceeded maximum operating temperature. Causes include heavy towing, sustained high-speed driving without adequate cooling, or a clogged transmission cooler. Requires Infiniti-capable scanner to read. Check cooler lines and external cooler condition.

Chassis and Brakes

  • C1101 — ABS wheel speed sensor fault, front right. Failed sensor, damaged tone ring, or wiring harness damage. On the QX60 and QX80, front wheel speed sensor failures are more common than rear due to brake heat proximity.
  • C1102 — ABS wheel speed sensor fault, front left. Same as C1101 on the opposite side.
  • C1103 — ABS wheel speed sensor fault, rear right. Rear sensor failures on the QX80 are often caused by corrosion at the sensor body mounting point.
  • C1130 — ABS control unit fault. The ABS module itself has detected an internal fault. On the G35 and G37, this code sometimes appears after a battery replacement due to voltage interruption during module initialisation. Disconnect the battery for 10 minutes before replacing the ABS module.
  • C1111 — ABS actuator motor circuit fault. The hydraulic ABS pump motor is not responding. Causes include a failed motor, relay fault, or ABS module fault. Requires ABS-capable scanner to diagnose sub-faults.

Electrical and Communication

  • B1018 — Airbag circuit fault (driver’s side). The SRS module has detected a fault in the driver airbag circuit. Causes include a faulty clockspring (most common on higher-mileage Q50 and QX60), wiring damage in the steering column, or a failed airbag module. The clockspring is the most frequent cause and is accessed through the steering wheel.
  • U1000 — CAN bus communication error. One or more modules cannot communicate on the CAN bus. Causes include a failing ECM, a dead battery causing communication disruption, or a wiring fault. On Infiniti, U1000 sometimes appears after battery replacement — disconnect the new battery for 10 minutes to allow the network to reinitialise before diagnosing further.
  • U1001 — CAN bus timeout. A module is not responding within the required time window. Often accompanies U1000. The module named in the sub-code identifies which component has failed or lost power. Requires Infiniti-capable scanner to read sub-codes.

How to Read Codes on Infiniti

The OBD2 port on all Infiniti vehicles is under the dashboard on the driver’s side. Generic OBD2 scanners read standard P0 codes. For Infiniti/Nissan-specific codes — P1xxx, C1xxx, B1xxx, and U1xxx — a scanner with Nissan/Infiniti manufacturer coverage is required. The factory tool is Nissan Consult III+, but capable aftermarket alternatives such as the Autel MX808 or Launch X431 read manufacturer-specific codes on these vehicles.

After fixing the fault, clear codes with the scanner. Disconnecting the battery clears codes but also resets emission readiness monitors — the vehicle needs several drive cycles before passing a state or emissions inspection.

Additional Engine and Emissions Codes

  • P0031 — Upstream O2 sensor heater circuit low, Bank 1. The heater element in the upstream sensor has failed or has a short to ground. Replace the upstream oxygen sensor. Common on VQ35DE past 100,000 miles.
  • P0037 — Downstream O2 sensor heater circuit low, Bank 1. Same as P0031 but on the post-catalyst sensor. Replace downstream O2 sensor; does not indicate converter failure on its own.
  • P0102 — MAF sensor circuit low input. The MAF signal is below the minimum expected voltage — often a disconnected sensor, torn intake boot, or wiring issue rather than a failed sensor. Check physical connections before replacing.
  • P0131 — Upstream O2 sensor low voltage, Bank 1. Lean exhaust condition detected at the upstream sensor. Causes include an exhaust leak near the sensor, vacuum leak, or failed sensor. On the FX35 and G35, exhaust manifold gasket leaks are a common cause at higher mileage.
  • P0133 — Upstream O2 sensor slow response, Bank 1. The sensor is responding too slowly to mixture changes — typically a worn sensor past 100,000 miles. Replace the upstream O2 sensor.
  • P0138 — Downstream O2 sensor high voltage, Bank 1. The post-catalyst sensor is reading consistently rich. Causes include a failed converter allowing unburned fuel through, or a failed downstream sensor. Confirm converter efficiency before replacing sensor.
  • P0174 — System too lean, Bank 2. Mirror of P0171 on the opposite bank. When P0171 and P0174 appear together on a V6, suspect a shared cause — dirty MAF sensor or a vacuum leak at the intake plenum rather than a bank-specific problem.
  • P0175 — System too rich, Bank 2. When appears with P0172, shared cause is more likely than bank-specific fault. Check MAF and thermostat first.
  • P0222 — Throttle position sensor B circuit low. One of two TPS signals in the electronic throttle body is reading low. On the Q50 and QX60 with drive-by-wire, this often points to a failing throttle body assembly. Cleaning the throttle body sometimes resolves it temporarily.
  • P0327 — Knock sensor circuit low, Bank 1. Open circuit or short in the knock sensor wiring. On the VQ35DE, the knock sensor wiring harness runs along the underside of the intake manifold and is prone to abrasion damage. Inspect harness routing before replacing sensor.
  • P0400 — EGR flow insufficient. The EGR system is not flowing the expected amount of exhaust gas during the test cycle. On Infiniti diesel variants sold outside North America, carbon buildup on the EGR valve is the primary cause.
  • P0412 — Secondary air injection system switching valve circuit fault. The air pump system has a fault — common on cold-climate models where the secondary air injection pump seizes from moisture. Pump replacement is the standard repair.
  • P0446 — EVAP vent control circuit. The EVAP canister vent valve is not opening or closing correctly. Causes include a stuck valve, wiring fault, or failed canister. On the QX60, this code sometimes accompanies P0448 when both the vent valve and canister need replacement.
  • P0491 — Secondary air injection insufficient, Bank 1. The secondary air pump is operating but not injecting adequate airflow. Causes include a clogged air injection port, a stuck combination valve, or a partially failed pump. Often appears alongside P0412.
  • P0506 — Idle RPM too low. Dirty throttle body, vacuum leak, or failed IACV. On the VQ35DE, the throttle body accumulates carbon deposits that restrict airflow at idle — cleaning resolves it in most cases.
  • P0562 — System voltage low. Failing battery, corroded terminals, or charging system fault. On the QX80 and QX56 with dual battery systems, one battery can fail while the other masks the fault until a cold morning or sustained electrical load reveals it.
  • P0600 — Serial communication link fault. The ECM is not communicating with one or more control modules on the internal data link. Causes include a failed ECM, a wiring fault, or a module that has lost its calibration. Often appears after a voltage spike or battery failure.
  • P0638 — Throttle actuator control range/performance. The electronic throttle body actuator is not responding within expected parameters. On the Q50 and QX60, this code can trigger a reduced throttle response mode. Clean throttle body first; replace if fault returns.
  • P1217 — Engine over temperature (Infiniti-specific). The ECM has detected an engine overheat condition through the coolant temp sensor. Requires Infiniti-capable scanner to read. Causes include a failed thermostat, low coolant, failed water pump, or blocked radiator. Do not continue driving — diagnose before restarting.
  • P1800 — Transmission control module power supply fault (Infiniti-specific). The TCM is not receiving adequate supply voltage. Causes include a blown fuse, corroded connector at the TCM, or a failing battery. Requires Infiniti scanner to read. Check TCM fuse and connector before replacing the module.

Additional Chassis Codes

  • C1104 — ABS wheel speed sensor fault, rear left. Same failure pattern as C1103. On the G35 and G37 sedan, rear wheel speed sensor failures are more common than on the SUV lineup due to different hub designs.
  • C1155 — Brake fluid pressure sensor fault. The ABS module is not receiving a valid signal from the brake pressure sensor. Causes include a failed sensor, low brake fluid, or ABS module fault. Replace sensor; check brake fluid level before diagnosis.
  • C1156 — Brake fluid level low. The ABS module has detected low brake fluid. Check fluid level and inspect for leaks at all four callipers and brake lines before topping up.

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