P1291: High Side #1 (Right) Short to Ground or B+
The P1291 code indicates a short circuit in the high side driver circuit for the right bank fuel injectors or ignition coils. This means the circuit is either shorted to ground or battery positive voltage (B+), causing the PCM to detect an abnormal voltage condition. This can lead to misfires, poor fuel economy, and potential damage to the PCM or other components.
01. Most Common Causes
- Short to ground in wiring or connector for right bank injectors/coils
- Short to B+ in wiring or connector
- Failed fuel injector or ignition coil on right bank
- Corroded or damaged connector
- Faulty PCM (rare)
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire or rough idle
- Reduced engine power
- Poor fuel economy
- Hard starting or no start
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect wiring and connectors for right bank injectors/coils for damage, corrosion, or shorts.
Step 3: Use a multimeter to check resistance and continuity of the high side circuit; compare to specs.
Step 4: Test each injector/coil on the right bank for internal shorts.
Step 5: If no issues found, check PCM for faults or perform a wiggle test.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause engine misfires, reduced performance, and potential damage to the PCM or catalytic converter.
How much does it cost to fix?▼
Repair costs typically range from $150 to $400, depending on the cause (wiring repair vs. component replacement) and labor rates.