Cylinder #3 Igniter Circuit Short (High to Low Side)
P1262 indicates a short circuit between the high and low sides of the ignition coil driver circuit for cylinder #3. This typically means the coil driver transistor inside the engine control module (ECM) or the ignition coil itself has failed, causing a direct short. The ECM monitors the current flow and detects an abnormal condition, setting this code. This can lead to misfires, poor performance, and potential damage to the ECM if not addressed.
01. Most Common Causes
- Faulty ignition coil on cylinder #3
- Short circuit in wiring between ECM and coil
- Failed ECM internal driver for cylinder #3
- Corrosion or damage at coil connector
02. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire on cylinder #3
- Rough idle or hesitation
- Reduced fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P1262 is present.
Step 2: Swap ignition coil #3 with another cylinder and clear codes. If code moves, replace coil.
Step 3: If code stays on #3, check resistance and continuity of wiring between ECM and coil connector.
Step 4: If wiring is good, test ECM driver circuit with a lab scope or test light; if shorted, ECM replacement may be needed.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a shorted ignition circuit can cause further damage to the ECM or catalytic converter due to misfire.
How much does it cost to fix?▼
Typically $150-$400, depending on whether the ignition coil ($50-$150) or ECM ($200-$400) needs replacement, plus labor.