P2CE3

Code

Generic P — Powertrain

Intake Air Heater C Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 35 RU: 22

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Page language: EN

Causes

Open circuit in heater C supply or ground
Short to ground in heater C control wiring
Short to battery voltage in control wiring
Failed intake air heater element (heater C)
Blown fuse or faulty heater relay
Corroded or loose connector or terminal

Symptoms

MIL (Check Engine Light) illuminated
Harder cold starts or extended cranking time in cold conditions
Rough or unstable idle after cold start
Reduced cold-start performance and higher white/blue smoke on some engines
Heater circuit(s) not drawing expected current (if measured)
DTC present in scan tool freeze-frame and failure counts

What to check

Read and record freeze-frame and pending/confirmed status with a scan tool
Visual inspection of intake air heater C connector, wiring, relay and fuse for damage/corrosion
Check fuse continuity and relay operation for heater supply circuit
Measure battery voltage at the heater supply relay/fuse with key ON and engine OFF
Measure resistance of the heater element between its terminals and to ground (with power disconnected)
Backprobe connector while commanding heater ON to measure supply and driver voltages/currents

Signal parameters

Supply voltage at heater fuse/relay: ~11–14.5 V (key ON/battery charged)
Heater element resistance (typical, varies by engine): usually low ohms (example 0.2–5 Ω); open/infinite indicates a failed element
Control/driver circuit voltage: may be near 0 V (low-side driver ON) or pulsed (PWM) — verify with scope if available
Current draw when commanded: expected to be several amperes (depends on heater design); near 0 A indicates open/high-resistance circuit
ECM command signal: digital/ground-switching output; should change state when heater is commanded ON

Diagnostic algorithm

Safety: Park vehicle, engage park/neutral, apply parking brake. Disconnect negative battery only if required for tests/repairs and follow manufacturer procedure.
Retrieve DTC(s) and freeze frame with a scan tool. Note related codes and engine conditions.
Perform a visual inspection of the intake air heater C connector, wiring harness, fuse(s) and relay. Look for corrosion, melted insulation, or signs of overheating.
Check the fuse for the heater circuit for continuity; replace if blown. Verify correct fuse rating before reinstalling.
With connector disconnected and power OFF, measure heater element resistance across its terminals. An open or infinite reading indicates a bad heater element.
Reconnect and backprobe the supply side of the heater at the connector. With key ON (engine OFF) confirm battery voltage is present at the supply terminal (≈11–14.5 V).
Command the intake air heater ON with a scan tool (if available) and observe voltages/currents: verify supply remains, and verify the ECM driver changes state (voltage/pulsing) or the circuit draws expected current. If no current is drawn but supply is present, suspect open wiring or failed element.
If the driver appears to hold the circuit low (or pulses) but voltage/current is absent at the heater connector, isolate wiring by checking continuity from connector to relay/fuse and to ground; repair any open/short.
Check for short to ground by measuring resistance from the control lead to chassis ground with the harness disconnected. Low resistance suggests a short.
Swap or bench-test the relay (if suspected) and re-test. If heater element and wiring check OK but circuit still fails, test/replace ECM driver only after confirming external circuit integrity.
After repairs, clear codes, perform the readiness test and re-check by commanding heater and/or performing a cold-start functional test to confirm correct operation.