What is Kato General Fault Code P0222?

Fault Code P0222 indicates a Throttle/Pedal Position Sensor/Switch "B" Circuit Low Input. This diagnostic trouble code means the Engine Control Module (ECM) has detected an abnormally low voltage signal from the secondary throttle position sensor circuit, typically below 0.5 volts when a higher reading is expected.

In Kato excavators, the Throttle Position Sensor (TPS) plays a critical role in communicating operator throttle input to the ECM. This sensor uses dual circuits (Circuit A and Circuit B) for redundancy and safety. When Circuit B reports voltage readings outside the expected range, the ECM triggers P0222 to prevent potential engine over-fueling or runaway conditions. This code directly impacts engine performance calibration, affecting fuel delivery, hydraulic pump control, and overall machine responsiveness.

Common Symptoms

Operators experiencing this fault code may notice:

• Engine derate or limp mode with significantly reduced power output and hydraulic function
• Erratic engine RPM response when moving the throttle lever, including hesitation or surging
• Check Engine Light (CEL) or malfunction indicator lamp illuminated on the instrument cluster
• Inability to achieve full throttle, with the engine limiting maximum RPM regardless of lever position
• Intermittent stalling during idle or when transitioning between operating modes

Potential Causes

The most common technical causes for P0222 in used Kato excavators include:

• TPS sensor degradation or internal failure due to age, heat exposure, or accumulated operating hours
• Wiring harness damage at known rub points near the engine mounting brackets or along the chassis frame rails
• Corroded or loose electrical connectors at the TPS sensor or ECM connections, common in machines exposed to moisture
• Short to ground in the sensor signal wire caused by insulation wear or pinched wiring
• ECM internal circuit issues (less common), particularly in high-hour machines with voltage spike history
• Poor ground connections at the sensor mounting point or ECM chassis ground

How to Troubleshoot and Fix Code P0222

Step 1: Visual Inspection and Connector Check Begin by locating the throttle position sensor on the fuel injection pump or throttle body. Inspect the wiring harness from the sensor to the ECM for visible damage, abraded insulation, or evidence of previous repairs. Check all connectors for corrosion, bent pins, or moisture intrusion—critical on used excavators with outdoor storage history.

Step 2: Electrical Testing with Multimeter Using a quality digital multimeter, backprobe the TPS Circuit B signal wire (consult your Kato wiring diagram for specific pin identification). With the ignition on and engine off, measure voltage while slowly moving the throttle lever. Circuit B should show a smooth voltage sweep typically between 0.5-4.5 volts. Readings stuck below 0.5 volts confirm the low circuit condition. Also check resistance between the signal wire and ground (should show infinite resistance/open circuit).

Step 3: Component and Ground Verification If wiring tests normal, verify the sensor ground circuit has less than 0.1 ohms resistance to chassis ground. For used excavators, remove the TPS sensor and inspect mounting surfaces for corrosion that could compromise grounding. Test the sensor independently using a TPS testing procedure with power supply and variable resistance measurement. If sensor fails testing or harness shows damage at common wear points, replace the faulty component and apply dielectric grease to all connectors before reassembly.

Step 4: Clear Codes and Verify Repair After repairs, clear fault codes using Kato diagnostic software or a compatible scan tool. Operate the machine through various throttle positions and load conditions for at least 20 minutes to ensure the code doesn't return.

---

Disclaimer: This guide provides general troubleshooting information. Always consult your Kato service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional damage or safety hazards.