DTC Advanced Diagnostics: P050B
DTC P050B: Cold Start Ignition Timing Control System Performance Problem
General Description
The quick warm-up system increases air flow and retards ignition timing to accelerate the warm-up of the catalyst on cold engine start. If the ignition timing is excessively advanced, the powertrain control module (PCM) detects a malfunction and stores a DTC.
Monitor Execution, Sequence, Duration, DTC Type
| Execution | Continuous |
| Sequence | None |
| Duration | 5.0 seconds or more |
| DTC Type | Two drive cycles, MIL on |
Enable Conditions
| Condition | Minimum | Maximum |
|---|---|---|
| Duration of quick warm-up system operation after engine start-up | - | 20 seconds |
| Engine coolant temperature [ECT Sensor 1] | 32°F (0°C) | 140°F (60°C) |
| Fuel feedback | Closed loop | |
| Throttle valve | Fully closed | |
| Accelerator pedal position | Released | |
| Other | Vehicle stopped | |
[ ]: HDS Parameter
Malfunction Threshold
The ignition timing is excessively advanced.
Possible Cause
The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
- Intake air duct breakage
- Intake air duct misinstalled
- Air cleaner breakage
- Air cleaner damage
- Air cleaner clogged
- Throttle body clogged
- Intake air system clogged
- Mass airflow (MAF) sensor failure
- Intake air temperature (IAT) sensor failure
- Engine coolant temperature (ECT) sensor 1 failure
- Air fuel ratio too rich
- Air fuel ratio to lean
- Ignition system failure
Confirmation Procedure
Operating Condition
- Leave the vehicle until the engine coolant temperature [ECT Sensor 1] lowers to 140°F (60°C) or less.
- Start the engine, and let it idle for at least 5 seconds.
Diagnosis Details
Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.
Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool clear command.