P0301 on a Nissan Altima
P0301 means cylinder 1 Misfire Detected. On the Altima, a few causes come up far more than others.
What P0301 usually means on a Altima
P0301 isolates a misfire to cylinder 1 on the Altima. Given the QR25's coil reputation, the coil for that cylinder is the prime suspect - swap it to a neighbor and see if the code follows. A single fouled plug is the next candidate. Persistent single-cylinder misfire will overheat the converter, which on this engine you especially want to avoid.
Most common causes on the Altima
- Failed ignition coil on cylinder 1
QR25 coils fail individually; the fault follows the coil when swapped.
- Fouled or worn plug
A lone overdue plug sets a single-cylinder code.
- Injector fault
A clogged injector isolates the misfire to one cylinder.
- Low compression on cylinder 1
Cat-debris scoring or valve wear can localize the miss on high-mileage QR25s.
What P0301 costs to fix on a Altima
Cylinder 1 is easy to reach and a coil is inexpensive, so a swap-and-replace is quick. Diagnosis stays cheap with a coil swap test. A compression problem - worth checking on older QR25s - is the costly exception.
Year, engine and mileage change the answer. Start a case and Redline weighs these causes against what your car shows, then names the check that would settle it.
Other codes on the Nissan Altima
Related symptoms
Nissan Altima problems & recalls by year
Based on widely reported patterns for this model; individual causes vary by year, engine and history. Generic P0301 behavior is covered on the main P0301 page. Confirm with a scan tool before buying parts.
P0301 on your Altima?
Every problem becomes a Case. Tell Redline what your Altima is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.