What does it mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. Although generic, specific repair steps may vary by make/model.
The throttle position sensor is a potentiometer that measures how much the throttle plate is open. When the throttle is opened, the reading (measured in volts) increases.
The powertrain control module (PCM) is the main computer controlling the vehicle and it provides a 5-volt reference signal to the throttle position sensor (TPS) and usually a ground as well. A general measurement is: at idle = 0.5 Volts; at full throttle = 4.5 Volts. If the PCM detects that the throttle angle is higher or lower than it should be for a specific RPM, it will set this code. The C refers to a particular circuit, sensor, or area of a particular circuit.
Potential Symptoms
Symptoms of a P0226 trouble code may include:
- Illumination of the Malfunction Indicator Lamp (MIL) (Check Engine Light or Service Engine Soon light)
- Intermittent stumbling during acceleration or deceleration
- Puff of black smoke during acceleration
- No start condition
A P0226 code can mean that one or more of the following events have occurred:
- TPS has an intermittent open or short internally
- Harness rubbing and causing an open or short in the wiring
- Poor connection to the TPS
- Faulty PCM (less likely)
- Water or corrosion in the connector or sensor
Possible Solutions
1. If you have access to a scan tool, see what the idle and WOT (wide open throttle) readings are for the TPS. Check if they are close to the specifications mentioned above. If not, replace the TPS and recheck.
2. Look for an intermittent open or short in the TPS signal. To do this, you cannot use a scan tool. You will need an oscilloscope. The reason is that scan tools take samples of many different readings over one or two data lines and might miss an intermittent break. Connect your oscilloscope and watch the signal. It should sweep up and down smoothly without glitches or spikes.
3. If no problem was found, perform a wiggle test. To do this, wiggle the connector and harness while observing the pattern. Does it drop out? If yes, replace TPS and recheck.
4. If you have no TPS signal, check for the 5-volt reference at the connector. If it is present, check if the ground circuit is open or shorted.
5. Make sure the signal circuit is not 12V. It should never have battery voltage. If it does, trace the circuit for a short and repair.
6. Look for water in the connector and replace TPS if necessary.