(M) Check Engine Lamp (MIL) will illuminate during engine operation if this Diagnostic Trouble Code was
recorded.
(G) Generator Lamp Illuminated
P1290
CNG Fuel System Pressure Too
High
Compressed natural gas system pressure above normal
operating range.
P1291
No Temp Rise Seen From Intake
Heaters
Energizing Heated Air Intake does not change intake air
temperature sensor an acceptable amount.
P1292
CNG Pressure Sensor Voltage Too
High
Compressed natural gas pressure sensor reading above
acceptable voltage.
P1293
CNG Pressure Sensor Voltage Too
Low
Compressed natural gas pressure sensor reading below
acceptable voltage.
P1294 (M)
Target Idle Not Reached
Target RPM not achieved during drive idle condition.
Possible vacuum leak or IAC (AIS) lost steps.
P1295
No 5 Volts to TP Sensor
Loss of a 5 volt feed to the Throttle Position Sensor has
been detected.
P1296
No 5 Volts to MAP Sensor
Loss of a 5 volt feed to the MAP Sensor has been
detected.
P1297 (M)
No Change in MAP From Start To
Run
No difference is recognized between the MAP reading at
engine idle and the stored barometric pressure reading.
P1298
Lean Operation at Wide Open
Throttle
A prolonged lean condition is detected during Wide Open
Throttle.
P1299 (M)
Vacuum Leak Found (IAC Fully
Seated)
MAP Sensor signal does not correlate to Throttle Position
Sensor signal. Possible vacuum leak.
P1388
Auto Shutdown Relay Control Circuit
An open or shorted condition detected in the ASD or CNG
shutoff relay control ckt.
P1389
No ASD Relay Output Voltage At
PCM
No Z1 or Z2 voltage sensed when the auto shutdown
relay is energized.
P1390 (M)
Timing Belt Skipped 1 Tooth or More
Relationship between Cam and Crank signals not correct.
P1391 (M)
Intermittent Loss of CMP or CKP
Loss of the Cam Position Sensor or Crank Position
sensor has occurred. For PL 2.0L
P1398 (M)
Mis-Fire Adaptive Numerator at Limit
PCM is unable to learn the Crank Sensor’s signal in
preparation for Misfire Diagnostics. Probable defective
Crank Sensor.
P1399
Wait To Start Lamp Cicuit
An open or shorted condition detected in the Wait to Start
Lamp circuit.
P1403
No 5 Volts to EGR Sensor
Loss of 5v feed to the EGR position sensor.
P1476
Too Little Secondary Air
Insufficient flow of secondary air injection detected during
aspirator test.(was P0411)
P1477
Too Much Secondary Air
Excessive flow of secondary air injection detected during
aspirator test (was P0411).
P1478 (M)
Battery Temp Sensor Volts Out of
Limit
Internal temperature sensor input voltage out of an
acceptable range.
P1479
Transmission Fan Relay Circuit
An open or shorted condition detected in the transmission
fan relay circuit.
P1480
PCV Solenoid Circuit
An open or shorted condition detected in the PCV
solenoid circuit.
P1482
Catalyst Temperature Sensor Circuit
Shorted Low
Catalyst temperature sensor circuit shorted low.
NS
EMISSION CONTROL SYSTEMS
25 - 9
DESCRIPTION AND OPERATION (Continued)
