Vacuum leak affecting only one bank, such as a cracked intake manifold gasket or deteriorated vacuum hose; Faulty upstream oxygen (O2) sensor on one bank providing inaccurate feedback; Leaking or clogged fuel injector on one bank causing uneven fuel delivery; Exhaust leak before the upstream O2 sensor on one bank, allowing outside air to skew readings; Mechanical engine issue such as low compression or a worn camshaft lobe on one bank; Contaminated mass airflow (MAF) sensor or dirty throttle body causing uneven air distribution; Wiring or connector problem in the O2 sensor circuit for one bank

DTC codes / Chrysler codes / P1170

P1170 · ChryslerBank To Bank Fuel Trim Offset

Q: What does code P1170 mean?

Bank To Bank Fuel Trim Offset. P1170 on Chrysler vehicles means the powertrain control module (PCM) has detected a significant difference in fuel trim between the left and right cylinder banks, exceeding a calibrated threshold. The PCM monitors short-term and long-term fuel trim values from both banks and sets this code when one bank requires substantially more or less fuel correction than the other, indicating an imbalance in air/fuel delivery or sensor feedback.

P1170 on Chrysler vehicles means the powertrain control module (PCM) has detected a significant difference in fuel trim between the left and right cylinder banks, exceeding a calibrated threshold. The PCM monitors short-term and long-term fuel trim values from both banks and sets this code when one bank requires substantially more or less fuel correction than the other, indicating an imbalance in air/fuel delivery or sensor feedback.

SystemPowertrain

Code typeChrysler specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering

Symptoms you may notice

Illumination of the malfunction indicator lamp (MIL) with no other noticeable symptoms
Rough idle or uneven engine operation, especially when cold
Slight hesitation or stumble during acceleration
Decreased fuel economy compared to normal
Occasional engine misfire or surging at steady speeds
Failed emissions test due to elevated hydrocarbon (HC) or carbon monoxide (CO) levels

Common causes, most likely first

Vacuum leak affecting only one bank, such as a cracked intake manifold gasket or deteriorated vacuum hose
Faulty upstream oxygen (O2) sensor on one bank providing inaccurate feedback
Leaking or clogged fuel injector on one bank causing uneven fuel delivery
Exhaust leak before the upstream O2 sensor on one bank, allowing outside air to skew readings
Mechanical engine issue such as low compression or a worn camshaft lobe on one bank
Contaminated mass airflow (MAF) sensor or dirty throttle body causing uneven air distribution
Wiring or connector problem in the O2 sensor circuit for one bank

How to diagnose and fix it

Perform a visual inspection of all intake and vacuum lines for cracks, loose connections, or disconnected hoses, paying close attention to bank-specific components.
Use a scan tool to check live fuel trim data for both banks and compare short-term and long-term values to confirm the imbalance.
Inspect the exhaust system for leaks before the upstream O2 sensors, especially at the manifold and downpipe flanges.
Test the upstream O2 sensors on both banks with a scan tool or oscilloscope to verify switching activity and response time.
Check fuel injectors for proper operation by performing a injector balance test or listening to each injector with a stethoscope.
Measure engine compression on both banks to rule out mechanical faults such as a failed head gasket or worn valve train.
Clean the MAF sensor and throttle body, then clear the code and verify that the fuel trim imbalance is resolved after a test drive.

What a bank-to-bank fuel trim offset really means

A P1170 does not automatically indicate a failed O2 sensor; a vacuum leak or exhaust leak on one bank is just as likely and often cheaper to fix.
Chrysler PCMs can set this code even when the overall fuel trim is within normal range, because the code focuses on the difference between banks rather than absolute values.
A dirty or failing mass airflow sensor can cause uneven fuel delivery that mimics a bank-specific problem, so always check MAF readings before replacing parts.
On some Chrysler engines, a failing intake manifold gasket can leak only when cold, causing a P1170 that appears intermittently and disappears after warm-up.
Replacing both upstream O2 sensors as a pair is often recommended when one fails, because the second sensor may be degraded and cause a repeat code.

Can I keep driving with P1170?

You can usually drive the vehicle short distances to a repair shop, but avoid heavy acceleration, towing, or prolonged idling until the fault is diagnosed. Continuing to drive with a significant fuel trim imbalance can lead to catalytic converter damage and worsened fuel economy.

Tools that help

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Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.