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Camaro Diagnostic Trouble Codes

This chart is to aid you in determining the cause of the dreaded "Service Engine Soon" light coming on. The first thing one must do is retrieve the code from the ECM. This is a simple procedure and all you need is a small piece of wire. Under the dash, on the same side of gas pedal is a connector and the A and B ports are the ones that needed to be jumped or connected together (see Diagram).

While the engine is off, connect A and B together with the wire then turn the ignition key to the position right before the starter is engaged. IMPORTANT: Do not start the engine with the wire in place, as this may damage the ECM (an expensive mistake!). The codes are two digits numbers and are cycled three times each. The first one that will always come up is the ECM reference pulse, code 12. It will be displayed as follows: One flash, then a short pause, then two flashes. This is repeated three times (cycles) then a short pause, then the next code is displayed in the same manner. To clear the ECM and the codes it displays, unplug the ECM fuse or the negative battery terminal for at least 30 seconds. After the power is reconnected, and the car started for the first time it may run a bit rough for a short period. This is normal, since the ECM is re-teaching itself. In order for the computer to get the proper information, you should drive the car around at light to medium throttle for 5 to 10 minutes at proper operating temperature.

Code Circuit Probable Cause
12 ECM Reference pulse
13 Oxygen Sensor Signal voltage is low; Lean during warm engine cruise
14 Cooolant Temperature Sensor Signal voltage is low
15 Cooolant Temperature Sensor Signal voltage is high
16 Battery Voltage Battery voltage is high
  Direct Ignition System DIS fault, line open or shorted to ground
17 RPM sensor RPM signal problem
21 Throttle Position Sensor (TPS) Signal voltage is high; Check for sticking or misadjusted TPS lever, or loose connections; Adjust or replace TPS
22 Throttle Position Sensor (TPS) Signal voltage is low; Check TPS adjustment; Replace TPS
23 Manifold Air Temperature Sensor (MAT) Signal voltage is low; Check MAT connections; Replace MAT
24 Vehicle Speed Sensor (VSS) Check sensor and wire connections for open circuit
25 Manifold Air Temperature Sensor (MAT) Signal voltage is low; Should be above 4 volts between MAT and ECM
27 2nd Gear Switch  
28 3rd Gear Switch  
29 4th Gear Switch  
31 Manifold Absolute Pressure Sensor (MAP) Signal voltage is low
32 Exhaust Gas Recirulation (EGR) System EGR solenoid should not be energized and vacuum should not pass to EGR valve; Replace EGR
33 Mass Air Flow Sensor (MAF) Signal voltage is high or excessive air flow; should be .5 volts at idle, 4.7 volts at WOT; Replace MAF power relay or MAF sensor
  Manifold Absolute Pressure Sensor (MAP) Signal voltage is high; Low vacuum sensed and engine misfire or irratic idle may cause this code, check vaccum hoses; Replace MAP
34 Mass Air Flow Sensor (MAF) Signal voltage is low or low air flow; should be .5 volts at idle, 4.7 volts at WOT; Replace MAF power relay or MAF sensor
  Manifold Absolute Pressure Sensor (MAP) Signal voltage is low or high vacuum; Check connections; Replace MAP
35 Idle Air Control Circuit (IAC) IAC system can not set desired RPM
36 Mass Air Flow Sensor (MAF) Burn-off circuit problem; Replace MAF burn-off relay
  Transmission Transmission shift problem
38 Brake switch Brake switch circuit failure
39 Torque Convertor Clutch (TCC) TCC circuit fault
41 Cylinder Select Error Check ignition control circuit. Check terminal D3 of ECM for proper connection to engine ground
42 Electronic Spark Timing If vehicle will not start, check wire connections between HEI module and ESTand by-pass terminal; Check connection at ignition module; Replace HEI module
43 Electronic Spark Control (ESC) Signal voltage is low; should be over 6 volts; check for loose connections
44 Oxygen Sensor (O2) Signal Voltage is high; exhaust is running lean, check O2 sensor wire, ECM connections; check throttle body gasket, intake manifold gaskets, vacuum hoses; Replace O2 sensor
45 Oxygen Sensor (O2) Signal voltage is low; Check charcoal canister for presence of fuel and vacuum control hose for fuel pressure regulator for presence of fuel; Replace O2 sensor
46 Vehicle Anit-Theft System (VATS) Make sure correct ignition key and procedure are being used; if engine won't turn over, have VATS checked be dealer
47 Electronic Control Module (ECM) ECM computer circuit problem, UART link
51 ECM PROM Make sure the PROM is properly installed in the ECM; if all pins are pushed in; Replace PROM or replace ECM
52 ECM Fuel CALPAK Make sure the CALPAK PROM is properly installed; Replace PROM
  Oil Temperature Sensor Signal voltage is low
53 System Over Voltage Check charging system
54 Fuel Pump Circuit Check fuel pump relay, circuit and connections, check oil pressure switch.
55 Electronic Control Module (ECM) Check that ECM ground connections are firmly connected; Replace ECM
58 Vehicle Anti-Theft System (VATS) VATS failure
61 Oxygen Sensor (O2) O2 sensor degraded or contaminated; Can be caused by fuel additive, improper lubricants, or sealants; Replace O2 sensor


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