Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Engine Controls - Tests W/Codes: Summary
If no hard fault codes are present (or only pass codes), driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.
| Code | Diagnostic Hints | ||
|---|---|---|---|
| 11 | Momentary Interruption Of Power Supply To ECU | ||
| 12 | No "G" or "NE" (RPM) Ignition Signal To ECU Within 2 Seconds After Engine Is Cranked | ||
| 13 | No "NE" (RPM) Ignition Signal To ECU When Engine Speed Is Greater Than Approximately 1000 RPM | ||
| 14 | No "IGF" Ignition Signal To ECU From Ignitor Several Times In Succession | ||
| 16 | Fault In Transmission/Transaxle ECU | ||
| 21 | Defective O2 Sensor, Open Or Short Circuit In O2 Sensor Signal | ||
| 22 | Open Or Short Circuit In Coolant Temp. Sensor Signal | ||
| 24 | Open Or Short Circuit In Intake Air Temp. Sensor Signal | ||
| 25 | Lean Signal Sent By O2 Sensor For Several Seconds | ||
| 26 | Rich Signal Sent By O2 Sensor For Several Seconds | ||
| 27 | Open Or Short Circuit In Sub-O2 Sensor Signal | ||
| 28 | Defective No. 2 O2 Sensor, Open Or Short Circuit In No. 2 O2 Sensor Signal | ||
| 31 | Open Or Short Circuit In Airflow Meter Or Vacuum Sensor Signal | ||
| 32 | Open Or Short Circuit Between Airflow Meter Terminals | ||
| 34 | Turbocharger Pressure Is Abnormal | ||
| 35 | Open Or Short Circuit In Turbocharger Pressure Sensor Or High Altitude Compensator Signal | ||
| 41 | Open Or Short Circuit In Throttle Position Sensor Signal | ||
| 42 | No "SPD" Signal From Vehicle Speed Sensor For Several Seconds With Engine Speed Approximately 2500-5500 RPM | ||
| 43 | No "STA" Signal To ECU Until Engine Reaches 800 RPM With Vehicle Not Moving | ||
| 51 | (1) Problem In One Of 3 Circuits Monitored By ECU | ||
| 52 | Open Or Short Circuit In Knock Sensor Signal | ||
| 53 | Knock Control In ECU Is Faulty | ||
| 71 | EGR Gas Below Predetermined Level During EGR Control | ||
|
|||
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.