| 88-93 5.0L VIN E TBI |
| Trouble code |
Fault location |
Probable cause |
| 13 |
Oxygen sensor voltage stays between 0.35 and 0.55 volts for 60 seconds.
Engine was at normal operating temperature and had been running for at least
2 minutes after start with a throttle angle above 5%. |
Wiring open circuit, O2S, ECM |
| 14 |
Coolant temperature sensor signal indicates a temperature of over 275°
F for 2 seconds. |
Wiring short circuit to ground, ECT sensor, ECM |
| 15 |
Coolant temperature sensor signal indicates a temperature colder than
-27° F for 30 seconds after the engine has been running for at least 30
seconds. |
Wiring open circuit, ECT sensor, ECM |
| 21 |
TPS voltage was above 2.5 volts for 8 seconds when the MAP sensor signal
showed manifold vacuum to be 15 pounds or more. |
Wiring open circuit/short circuit to positive, TP sensor, ECM |
| 22 |
TPS voltage was under 0.2 volts for when the engine was running. |
Wiring open circuit/short circuit to ground, TP sensor, ECM |
| 23 |
Inlet air temperature sensor signal showed an air temperature below -22°
F after the engine has been running for 5 minutes. |
Wiring open circuit, IAT sensor, ECM |
| 24 |
When engine speed was between 1200 and 4400 RPM and throttle position
angle was less than 3%, the MAP signal showed low voltage (high manifold
vacuum) for at least 5 seconds. |
Wiring open circuit/short circuit to ground, VSS, ECM |
| 25 |
Inlet air temperature sensor signal showed an air temperature over 302°
F after the engine has been running for 5 minutes. On Brougham models the
inlet air temperature sensor signal shows a temperature above 297° F with
an engine speed greater than 35 MPH. |
Wiring short circuit to ground, IAT sensor, ECM |
| 32 |
EGR open command did not change the MAP sensor signal. Normal EGR flow
should cause slight decrease in manifold vacuum which would change MAP sensor
signal. |
Wiring open circuit/short circuit to ground, supply wire, EGR valve, ECM |
| 33 |
MAP sensor signal voltage was too high (low vacuum) for 5 seconds when
throttle opening was under 4%. |
Wiring short circuit to positive, hose blocked/leaking, MAP sensor, ECM |
| 34 |
MAP sensor signal voltage was too low (high vacuum) when engine speed
was over 1200 RPM. |
Wiring open circuit/short circuit to ground, MAP sensor, ECM |
| 42 |
The EST signal did not change when the ECM applied bypass voltage to the
ignition module. |
Wiring open circuit/short circuit to ground, ICM, ECM |
| 43 |
The ECM did not detect a knock signal during near wide open throttle operation
with coolant temperature above 194° F or the knock signal was present for
4 seconds or more during normal engine operation. |
Wiring open circuit/short circuit to ground/short circuit to positive, KS incorrectly fitted, KS, insecure PROM, ECM |
| 44 |
Oxygen sensor voltage was under 0.25 volts for 50 seconds of closed loop
operation. On Brougham models the oxygen sensor voltage was under 0.2 volts. |
Wiring open circuit/short circuit to ground, injector(s) blocked, fuel contamination, fuel pressure low, exhaust system leaking, O2S, ECM |
| 45 |
Oxygen sensor voltage was over 0.75 volts for 30 seconds with a throttle
angle above 20%. On Brougham models the oxygen sensor voltage was over 0.7
volts. |
Wiring open circuit, fuel pressure high, injector(s) leaking, O2S contamination, EVAP canister purge valve, TP sensor, EGR system, O2S, ECM |
| 51 |
PROM error. |
Insecure PROM, incorrect PROM, ECM |
| 54 |
Fuel pump voltage was not present at fuel pump sense line for 2 seconds
after the ECM has sent the fuel pump on command. |
Wiring open circuit/short circuit to ground, fuel pump relay, engine oil pressure warning lamp switch |
| 55 |
ECM error. Replace ECM. |
ECM |
