Bank 2 Misfire Risking Catalyst Damage
This manufacturer-specific diagnostic trouble code indicates that the powertrain control module (PCM) has detected a severe misfire rate on Bank 2, posing an imminent risk of thermal damage to the catalytic converter. The misfire monitor evaluates crankshaft speed fluctuations between combustion events; when the irregularity exceeds the calibrated threshold for catalyst protection, the PCM sets this code. Bank 2 refers to the cylinder bank opposite the one containing cylinder No. 1 in V-type engines. This condition reflects persistent incomplete combustion that sends unburned hydrocarbons into the catalytic converter, drastically raising its internal temperature and potentially melting or degrading the substrate.
01. Most Common Causes
- Worn or failing ignition coils on Bank 2 cylinders
- Worn, contaminated, or incorrectly gapped spark plugs on Bank 2
- Clogged or uneven-flow fuel injectors on Bank 2
- Loss of compression in Bank 2 cylinders (piston rings, valves, head gasket)
- Vacuum leak or unmetered air intake affecting only Bank 2 mixture
- Low-octane, contaminated, or poor-quality fuel
- Faulty or interfering crankshaft position (CKP) or camshaft position (CMP) sensor signal
- Short, open, or corroded wiring in the misfire monitor circuit
- Previously degraded or melted catalytic converter on Bank 2 due to recurrent misfires
02. Symptoms You Will Notice
- Check Engine Light illuminated with code P1340
- Engine misfire, rough idle, hesitation, or loss of power
- Increased fuel consumption and emissions
- Possible smell of unburned fuel from exhaust
03. Step-by-Step Diagnosis
Scan for additional codes and freeze frame data to identify affected cylinders
Inspect spark plugs and ignition coils on Bank 2 for wear or damage
Perform a compression test on Bank 2 cylinders
Check fuel injector operation and flow on Bank 2
Inspect for vacuum leaks or intake air leaks on Bank 2
Verify CKP and CMP sensor signals and wiring integrity
Monitor misfire counts with a scan tool while test driving
1. Frequently Asked Questions
Is it safe to drive?▼
No, driving with this code is not safe. The severe misfire can quickly destroy the catalytic converter, leading to costly repairs and potential exhaust blockage.
How much does it cost to fix?▼
Repair costs vary widely depending on the cause, typically ranging from $150 for a simple spark plug replacement to $1,500 or more if the catalytic converter needs replacement.