P0300 on Infiniti: How to Diagnose & Fix
Random/Multiple Cylinder Misfire Detected
3 Infiniti models · 4 documented issues · 3 critical · $150-$14,000 repair
P0300 on Infiniti by model: symptoms, diagnosis and fix
The Hitachi coil-on-plug units on the VQ37VHR are a recurring failure item on higher-mileage G37s. Heat and electrical stress cause the coil body to blister or bulge, producing a random or single-cylinder misfire, rough idle and flashing check-engine light. Infiniti bulletin ITB11-017A, written for the FX35 (not the G37), ties P0300-P0306 misfires and blistered coils to poor engine grounds and battery cables, and owners and parts guides apply the same logic to the G37. On the G37 the coils are reached by removing the engine cover, airbox, intake tube and moving the throttle body aside; the middle coil on each bank is the hardest to get to.
Common Symptoms
- Rough idle or shaking at idle
- Flashing check engine light under load
- Misfire counts on one or more cylinders
- Hesitation and power loss
How to Fix
Replace the failed coil (and inspect all six for blistering); most shops replace all six with spark plugs once the first fails past 80k miles. Use OEM Hitachi coils; aftermarket units have a poor reputation on this engine. If coils fail repeatedly, check engine grounds. No recall.
Sources for this issue (6)
- p0300 missfire on g37 - MyG37forum
- P0300 & P0303 codes, No relief in sight - MyG37forum
- P0300 Random Multiple misfire - NICOclubforum
- P0300 on 2008-2013 Infiniti G37: Random Misfire Causes and Fixes (references ITB11-017A)article
- Infiniti ITB11-017A - Blistered ignition coils with misfire DTC (FX35)tsb
- How to Replace Ignition Coils 2008-2013 Infiniti G37 3.7L V6 - 1A Autoarticle
On pre-2012 VQ37VHR engines the oil gallery gaskets (the T- and L-shaped gaskets that seal the timing chain cover to the block) crack and fail, and unlike an ordinary external oil leak this one matters mechanically: the internal leak path bleeds down oil pressure feeding the top end. Low oil pressure on this engine starves the VVEL assembly and the cam and rod bearings, and owners who dismiss the warning have lost engines to it. There is often no early sign; what owners see is a low oil pressure warning or gauge reading that comes up at idle when hot, limp mode, and valve timing codes such as P0011 and P0021. Oil in the spark plug wells or on the exhaust manifolds points to a separate cam cover gasket leak, not this failure.
Common Symptoms
- Low oil pressure warning, especially at hot idle
- Engine enters limp mode
- Check engine light with P0011 or P0021
- Sudden oil pressure drop with no prior warning
How to Fix
Treat any low oil pressure indication on a pre-2012 G37 as urgent rather than cosmetic, and stop driving the car. Verify actual oil pressure with a mechanical gauge rather than trusting the dash indication before and after the repair; if a new oil pressure switch does not clear the warning, test pressure specifically for this gasket failure. Replace the oil gallery gaskets behind the timing chain cover with the revised OEM parts or an updated gallery gasket kit. If pressure remains low with the gaskets fixed, investigate the oil pump and pickup, since continued operation at low pressure will destroy the bearings.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- OEM VQ37VHR valve-cover gasket and tube-seal selectionsOEM13270-EY01A / 13270-EY01B / 13271-EY00A
Confirmed external valve-cover leak repair with selectable left/right gaskets and tube seals Fitment/availability: Fits 2008-2013 G37 Coupe and the listed later Sedan/Convertible VQ37VHR branches.
- OEM VQ37VHR valve-cover and gasket kitOEMZ1 assembled OEM VQ37VHR valve-cover kit
Do not replace sound covers merely because the serviceable perimeter gasket leaks; confi
- Nissan OEM fluid-gasket RTVOEMNissan OEM fluid gasket RTV
Small specified-joint sealant branch for the valve-cover procedure Fitment/availability: Use only at the service-manual junctions and in the specified bead size; it does not replace molded cover gaskets and excess RTV can contaminate oil…
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Sources for this issue (2)
The 5.6L VK56VD engine can develop timing chain stretch, particularly when oil changes are neglected. The primary and secondary timing chains elongate over time, causing rough idle, reduced power, and potential engine damage if not addressed.
Common Symptoms
- Rattling noise at cold start
- Check engine light with timing codes
- Rough idle
- Reduced engine power
How to Fix
Replace the timing chain, tensioners, and guides as a complete kit. This is a labor-intensive repair requiring significant engine disassembly. Strict adherence to 5,000-mile oil change intervals helps prevent premature chain wear.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Infiniti right/passenger camshaft timing chainOEM13028-1LA6A
Confirmed right-bank chain wear/damage branch Fitment/availability: 13028-1LA6A is the current Japan-made passenger/right timing chain replacing 1LA3A/1LA4A and is cataloged for 2014-2024 QX80 VK56VD. Confirm the 2014-2017 VIN, measured …
- Genuine Infiniti left/driver camshaft timing chainOEM13028-1CA6A
Confirmed left-bank chain wear/damage branch Fitment/availability: 13028-1CA6A is the current Japan-made driver/left timing chain replacing 1CA3A/1CA4A and is cataloged for 2014-2024 QX80 VK56VD. Confirm the 2014-2017 VIN, measured fault…
- Genuine Infiniti right/passenger timing-chain tensionerOEM13070-1LA2B
The retailer page confusingly calls it a belt tensioner; rely on the OE diagram and confirm VIN/position before ordering.
- Genuine Infiniti left/driver timing-chain tensionerOEM13070-1CA2C
Confirm the 2014-2017 VIN and position in the current diagram.
- Genuine Infiniti right-bank tension-side chain guideOEM13085-1LA3A
Confirm VIN and right-bank position.
- Genuine Infiniti right-bank slack-side chain guideOEM13091-1LA3A
Confirm VIN and right-bank position.
- Genuine Infiniti left-bank tension-side chain guideOEM13085-1CA2B
Confirm VIN and left-bank position.
- Genuine Infiniti left-bank slack-side chain guideOEM13091-1CA2B
Confirm VIN and left-bank position.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (1)
Nissan issued a large 2025 recall (NHTSA 25V-437, filed June 27, 2025) covering VC-Turbo vehicles including the 2022 Infiniti QX55, 2019-2022 QX50 and 2019-2020 Altima, plus the 1.5L Rogue. A suspected manufacturing defect in the crankshaft main bearing and the A-, C- and L-link bearings of the variable-compression mechanism can damage those bearings. In the worst case a bearing seizes or a failed bearing breaches the engine block, causing catastrophic engine failure. This is a distinct defect from the previously documented oil-consumption issue. Nissan also announced a VC-Turbo warranty extension (10 years/120,000 miles on the long block for the 2022 QX55). Symptoms often precede failure and out-of-warranty engine replacements have run five figures.
Common Symptoms
- Engine knocking or ticking noise
- Metal shavings/debris in engine oil
- Diesel-like pinging at idle
- Sudden loss of power / stalling
- Illuminated check-engine or malfunction light
- Engine seizure
How to Fix
Have the VIN checked for the recall. The remedy reprograms the ECM, scans for diagnostic codes, and inspects the oil pan for metal debris; if metal is found the engine is replaced free of charge. Owners should keep to strict oil-change intervals, use the correct 0W-20 spec oil, and stop driving immediately if knocking, ticking or metal in the oil is noticed. Because a warranty extension applies, keep all service records to protect coverage.
Sources for this issue (3)
P0300 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0300 mean on a Infiniti?
P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On Infiniti it is documented across 3 models: G37, QX80, QX55.
What are the most common causes of P0300?
The most common causes of P0300 are: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor, Clogged or dirty fuel injectors, Faulty crankshaft/camshaft position sensor, Low compression or EGR/PCV system faults. The specific cause varies by vehicle.
How much does it cost to fix P0300 on a Infiniti?
Published repair estimates on Infiniti range from $150 to $14,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.