Honda P1167 Code: A/F Sensor (Sensor 1) Heater System Malfunction
The upstream A/F sensor heater is powered but isn't drawing the current or heating the sensor as expected.
At a glance
Severity: Low
- Meaning
- A/F Sensor (Sensor 1) Heater System Malfunction
- System
- Fuel & Air Metering · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $20–$550
- DIY difficulty
- Moderate
While P1166 covers the heater's electrical circuit, P1167 is about how the heater performs. The PCM checks the current the A/F sensor heater pulls and, depending on the model, how quickly the sensor element comes up to working temperature; if the current is out of range or warm-up is too slow even though the circuit looks intact, it stores P1167. An aging heater whose resistance has drifted is the usual reason, but low charging voltage and voltage drop across burned relay contacts or heat-damaged connector pins can starve a healthy heater. On its own, P1167 is worth a few voltage measurements before buying a sensor; together with P1166 it almost always means the sensor itself.
Can I keep driving? Driving is fine. Expect a little more fuel use on short trips, and fix it before your next emissions inspection.
How to read P1167
- P Powertrain
- 1 Manufacturer-specific
- 1 Fuel & air metering
- 67 Specific fault
Symptoms
- Check engine light, typically after a cold start in cool weather
- Code sometimes returns only in winter or on short trips
- Slightly higher fuel consumption
- Charging voltage lower than normal on some affected cars
- No noticeable change in engine behavior
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- A/F sensor heater aged, resistance out of range or intermittently open
- Voltage drop from burned A/F heater relay contacts
- Heat-damaged or loose heater pins in the sensor connector
- Low system voltage from a weak battery or failing alternator
- Exhaust leak ahead of the sensor cooling the tip
- PCM heater monitoring fault
Diagnosis step by step
Check charging voltage first
With the engine running and the headlights and blower on, charging voltage should stay roughly between 13.5 and 14.8 V. A system sagging toward 12 V can't feed the heater properly and sets P1167 on a healthy sensor.
Tools: Multimeter
Do a voltage drop test at the heater
With the engine running and the heater on, back-probe the heater feed at the sensor connector and compare it to battery voltage. More than about 0.5 V of difference points to relay contacts, a fuse terminal or a connector pin with high resistance.
Tools: Multimeter
Inspect the connector for heat damage
The heater current is high enough to cook a loose pin. Unplug the connector and look for browned plastic, discolored or loose heater terminals, and fix or replace the connector if you find any.
Tools: Flashlight, Screwdriver
Measure the heater cold and warm
Measure the heater resistance with the engine cold, then again after a short run. A reading far off spec, or one that jumps to open as it warms, confirms an aging heater even if it tests fine at room temperature.
Tools: Multimeter
Check for exhaust leaks and replace the sensor
Listen and feel for ticking leaks at the manifold gasket or flange ahead of the sensor, since cold air there slows warm-up. If the power supply and connector are sound, replace the A/F sensor with the correct wideband part.
Tools: Flashlight, O2 sensor socket
Where the parts are
- 1Battery
- 2Alternator
- 3Engine computer (ECM)
- 4CAN bus
- 5Transmission
- 6Wheel speed sensor
- 7High-voltage battery
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Test and replace weak battery | Yes | $150–$300 |
| Replace A/F heater relay or repair connector pins | Yes | $20–$200 |
| Replace A/F sensor yourself (OE-type part) | Yes | $90–$250 |
| Replace A/F sensor at a shop | No | $250–$550 |
| Repair exhaust manifold gasket leak | No | $200–$500 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
A stored P1167 lights the check engine light and fails an OBD emissions test. The heater and O2 sensor monitors need a few cold starts after the repair to show ready.
Frequently asked questions
P1167 appears only in winter. Why?
In cold weather the heater has more work to do, and a marginal heater, weak battery or high-resistance connection can't bring the sensor up to temperature within the PCM's time limit. In summer the same weak heater may just scrape through.
Can a bad alternator cause P1167?
It can. The A/F sensor heater is one of the bigger electrical loads on the engine, and if charging voltage is low, the heater current falls below what the PCM expects. Test charging before replacing the sensor.
I only have P1167, not P1166. Is the sensor still bad?
Probably, but check supply voltage and voltage drop first. With P1167 alone the circuit is usually intact, so the question is whether the heater is weak or simply isn't getting enough voltage.
How long does a Honda A/F sensor usually last?
Often well over 100,000 miles, but heaters do age. Frequent short trips, oil burning and coolant contamination shorten sensor life.
Sources
- Manufacturer public service information (cross-checked)
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