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.
1994 Toyota Corolla Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Engine Controls - Tests W/Codes
- Introduction
- Self-Diagnostic System
- Trouble Code Diagnostic Hints
- Trouble Code Identification
- Trouble Code Charts
- ECM Terminal Identification
- Diagnostic Circuit Check ("Te1" & "Te2" Terminal Circuit)
- ECM Power Source Circuit Check
- ECM Back-Up Power Source Circuit Check
- DTC 12 - Rpm Signal
- DTC 13 - Rpm Signal
- DTC 14 - Ignition Signal
- DTC 16 - Electronic-Controlled A/T Signal
- DTC 21- Oxygen Sensor Circuit
- DTC 22 - Engine Coolant Temperature Sensor Signal
- DTC 24 - Intake Air Temperature Sensor
- DTC 25/26 - Lean Or Rich Air/Fuel Mixture
- DTC 27 - Sub-Oxygen Sensor Signal
- DTC 31 - Map Sensor Signal
- DTC 41 - Throttle Position Sensor Signal
- DTC 42 - Vehicle Speed Sensor Signal
- DTC 43 - Starter Signal
- DTC 51 - Switch Condition Signal
- DTC 52 - Knock Sensor Signal (1.8L)
- DTC 71 - EGR System Malfunction
- Summary
Factory Service Tools
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.
Comes to youSame-day available12-month warranty
Get a Free QuoteNo obligation. See pricing before you book.