Cause
High resistance in sensor wiring
A connection that still conducts but no longer conducts freely — a corroded terminal, a spread contact, a strand-broken wire under intact insulation. This is the most deceptive wiring fault there is, because continuity tests pass. A meter reading a complete circuit says nothing about how much voltage that circuit drops once real current flows through it.
On a signal wire the effect is a reading that is consistently wrong rather than absent, which is why it so often presents as a drifted or correlating-badly sensor and gets a new sensor fitted for nothing. On a heater or supply circuit it is worse, because the resistance turns into heat at the bad joint, which oxidises it further and accelerates its own decline until the terminal burns.
Voltage-drop testing under load is what finds it, not a continuity check. And a connector showing discoloured or melted plastic around one terminal has already declared itself — that browning is the visible history of a connection that has been failing for a long time.
Typically a moderate job.
Codes this can cause (36)
Codes where this is a likely explanation first, rather than merely a possible one.
- P00D2 O2 Sensor Heater Control Circuit Range/Performance Bank 1 Sensor 2 Likely for this code Moderate
- P01BA Engine Oil Temperature Sensor B Range/Performance Likely for this code Moderate
- P062A Fuel Pump A Control Circuit Range/Performance Likely for this code High
- P06B9 Cylinder 1 Glow Plug Circuit Range/Performance Likely for this code Moderate
- P06BA Cylinder 2 Glow Plug Circuit Range/Performance Likely for this code Moderate
- P06BB Cylinder 3 Glow Plug Circuit Range/Performance Likely for this code Moderate
- P06BC Cylinder 4 Glow Plug Circuit Range/Performance Likely for this code Moderate
- P06BD Cylinder 5 Glow Plug Circuit Range/Performance Likely for this code Moderate
- P06BE Cylinder 6 Glow Plug Circuit Range/Performance Likely for this code Moderate
- P2244 O2 Sensor Reference Voltage Performance Bank 1 Sensor 1 Likely for this code High
- P2248 O2 Sensor Reference Voltage Performance Bank 2 Sensor 1 Likely for this code High
- P2253 O2 Sensor Negative Current Control Circuit High Bank 1 Sensor 1 Likely for this code High
- P2256 O2 Sensor Negative Current Control Circuit High Bank 2 Sensor 1 Likely for this code High
- P22A7 NOx Sensor Heater Sense Circuit Range/Performance Bank 1 Sensor 2 Likely for this code Moderate
- P24B7 Particulate Matter Sensor Heater Resistance Likely for this code Moderate
- P24C2 Exhaust Gas Temperature Measurement System - Multiple Sensor Correlation Bank 1 Likely for this code Moderate
- P24C7 Particulate Matter Sensor Temperature Circuit Range/Performance Likely for this code Moderate
- P000C A Camshaft Position Slow Response Bank 2 Moderate
- P009A Intake Air Temperature/Ambient Air Temperature Correlation Moderate
- P00B2 Radiator Coolant Temperature Sensor Circuit Range/Performance Moderate
- P011B Engine Coolant Temperature/Intake Air Temperature Correlation Moderate
- P040B Exhaust Gas Recirculation Temperature Sensor A Circuit Range/Performance Moderate
- P040F Exhaust Gas Recirculation Temperature Sensor A/B Correlation Moderate
- P046C Exhaust Gas Recirculation Sensor A Circuit Range/Performance Moderate
- P058C Battery Monitor Module Temperature Monitoring Performance Moderate
Information, not instruction
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