Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P050B: Cold Start Ignition Timing Control System Performance Problem
- Turn the ignition switch to ON (II).
- Check for Pending or Confirmed DTCs with the HDS.
Are any Pending or Confirmed DTCs other than P050B indicated?
YES: Go to the indicated DTC's troubleshooting.
NO: Go to step 3.
- Check for poor connections or a blockage at the intake air duct.
Is it OK?
YES: Go to step 4.
NO: Reconnect or repair the intake air duct, then go to step 24.
- Check for damage at the air cleaner housing.
Is it OK?
YES: Go to step 5.
NO: Replace the air cleaner housing (see AIR CLEANER REMOVAL/INSTALLATION ), then go to step 24.
- Check for dirt or debris in the air cleaner element.
Is it dirty?
YES: Replace the air cleaner element or remove the debris (see AIR CLEANER ELEMENT INSPECTION/REPLACEMENT ), then go to step 24.
NO: Go to step 6.
- Let the engine cool until the value of ECT SENSOR 1 is 122°F (50°C) or less.
- Clear the DTC with the HDS.
- Start the engine, and let it idle for 10 seconds or more.
- Monitor the OBD STATUS for DTC P050B in the DTCs MENU with the HDS.
Does the screen indicate FAILED?
YES: Go to step 10.
NO: If the HDS indicates PASSED, intermittent failure, the system is OK at this time. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 6.
- Inspect the ignition timing (see IGNITION TIMING INSPECTION
).
Is the ignition timing OK?
YES: Go to step 12.
NO: Go to step 11.
- Check for damage at the CKP sensor (see CKP SENSOR REPLACEMENT
) and the CKP sensor pulser plate (see CKP PULSE PLATE REPLACEMENT
).
Is the CKP sensor and/or the CKP sensor pulser plate damaged?
YES: Replace the CKP sensor (see CKP SENSOR REPLACEMENT ) and/or the CKP sensor pulser plate (see CKP PULSE PLATE REPLACEMENT ), then go to step 25.
NO: Go to step 31.
- Do the ETCS TEST in the INSPECTION MENU with the HDS.
Is the THROTTLE ACTUATOR CONTROL VALVE normal?
YES: Go to step 13.
NO: Replace the throttle body (see THROTTLE BODY REMOVAL/INSTALLATION ), then go to step 24.
- Start the engine. Hold the engine speed at 3, 000 rpm without load (A/T in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
- While holding the engine speed at 2, 500 rpm for 30 seconds, check the MAF SENSOR in the DATA LIST with the HDS.
Is there about 4.6 - 5.7 gm/s (M/T) or 4.7-5.7 gm/s (A/T)?
YES: Go to step 15.
NO: Replace the MAF sensor/IAT sensor (see MAF SENSOR/IAT SENSOR REPLACEMENT ), then go to step 24.
- Turn the ignition switch to LOCK (0).
- Drain the coolant (see COOLANT CHECK ).
- Remove ECT sensor 1 (see ECT SENSOR 1 REPLACEMENT ), and ECT sensor 2 (see ECT SENSOR 1 REPLACEMENT ).
- Allow the sensors to cool to the ambient temperature.
- Note the ambient temperature.
- Connect ECT sensor 1 and ECT sensor 2 to their 2P connectors, but do not install them.
- Turn the ignition switch to ON (II).
- Note the value of ECT SENSOR 1 and ECT SENSOR 2 quickly in the DATA LIST with the HDS.
- Compare the value of ECT SENSOR 1 and the ambient temperature, and the value of ECT SENSOR 2 and the ambient temperature individually.
Does either sensor differ more than 5.4°F (3°C) from the ambient temperature?
YES: Replace the sensor that differed more than 5.4°F (3°C) from the ambient temperature, then go to step 24.
NO: Refill the coolant (see COOLANT CHECK ), then check for and repair any problems with the following items. If the items are OK, go to step 24.
- Engine compression and cylinder leakdown
- VTEC system
- Engine oil
- A/C system
- Power steering
- Turn the ignition switch to ON (II).
- Reset the ECM/PCM with the HDS.
- Do ECM/PCM IDLE LEARN PROCEDURE .
- Let the engine cool until the value of ECT SENSOR 1 is 122°F (50°C) or less.
- Start the engine, and let it idle for 10 seconds or more.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P050B indicated?
YES: Check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF sensor/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1.
NO: Go to step 30.
- Monitor the OBD STATUS for DTC P050B in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES: Troubleshooting is complete. If any other Pending or Confirmed DTCs were indicated in step 29, go to the indicated DTC's troubleshooting.
NO: If the HDS indicates FAILED, check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF sensor/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM, then go to step 1. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 27.
- Update the ECM/PCM if it does not have the latest software (see ECM/PCM UPDATE ), or substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ).
- Do ECM/PCM IDLE LEARN PROCEDURE .
- Let the engine cool until the value of ECT SENSOR 1 is 122°F (50°C) or less.
- Start the engine, and let it idle for 10 seconds or more.
- Check for Pending or Confirmed DTCs with the HDS.
Is DTC P050B indicated?
YES: Check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF sensor/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 33. If the ECM/PCM was substituted, go to step 1.
NO: Go to step 36.
- Monitor the OBD STATUS for DTC P050B in the DTCs MENU with the HDS.
Does the screen indicate PASSED?
YES: If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM (see ECM/PCM REPLACEMENT ). If any other Pending or Confirmed DTCs were indicated in step 35, go to the indicated DTC's troubleshooting.
NO: If the HDS indicates FAILED, check for poor connections or loose terminals at the CKP sensor, the throttle body, the MAF sensor/IAT sensor, ECT sensor 1, ECT sensor 2, and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM (see SUBSTITUTING THE ECM/PCM ), then go to step 33. If the ECM/PCM was substituted, go to step 1. If the HDS indicates EXECUTING, keep idling until a result comes on. If the HDS indicates OUT OF CONDITION or NOT COMPLETED, go to step 33.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
Rather have a pro handle this?
A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.
No obligation. See pricing before you book.