Possible False Code 42

Some 1984 Cutlass Supreme, 88 and 98 models with 5.0 engine may experience a false Code 42 on the CEC diagnostic readout. This condition may be caused by routing EST wiring next to and around spark plug wiring. To correct this condition, reroute EST wiring around firewall side of transmission filler tube.

Fig 1: Code 42: Electronic Spark Timing (EST) Flow Chart

Fig 2: Code 42: Electronic Spark Timing (EST) Flow Chart